{"trustable":true,"prependHtml":"\u003cstyle type\u003d\u0027text/css\u0027\u003e\n .input, .output {\n border: 1px solid #888888;\n }\n .output {\n margin-bottom: 1em;\n position: relative;\n top: -1px;\n }\n .output pre, .input pre {\n background-color: #EFEFEF;\n line-height: 1.25em;\n margin: 0;\n padding: 0.25em;\n }\n \u003c/style\u003e\n \u003clink rel\u003d\"stylesheet\" href\u003d\"//codeforces.org/s/96598/css/problem-statement.css\" type\u003d\"text/css\" /\u003e\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript type\u003d\"text/javascript\" async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS_HTML-full\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cp\u003eYou found a mysterious function \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e\u003c/span\u003e. The function takes two strings \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003es\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e1\u003c/sub\u003e\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003es\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e2\u003c/sub\u003e\u003c/span\u003e. These strings must consist only of lowercase English letters, and must be the same length.\u003c/p\u003e\u003cp\u003eThe output of the function \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e\u003c/span\u003e is another string of the same length. The \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/span\u003e-th character of the output is equal to the minimum of the \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/span\u003e-th character of \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003es\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e1\u003c/sub\u003e\u003c/span\u003e and the \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/span\u003e-th character of \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003es\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e2\u003c/sub\u003e\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eFor example, \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003c/span\u003e\"\u003cspan class\u003d\"tex-font-style-tt\"\u003eab\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003eba\u003c/span\u003e\"\u003cspan class\u003d\"tex-span\"\u003e)\u003c/span\u003e \u003d \"\u003cspan class\u003d\"tex-font-style-tt\"\u003eaa\u003c/span\u003e\", and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003c/span\u003e\"\u003cspan class\u003d\"tex-font-style-tt\"\u003enzwzl\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003ezizez\u003c/span\u003e\"\u003cspan class\u003d\"tex-span\"\u003e)\u003c/span\u003e \u003d \"\u003cspan class\u003d\"tex-font-style-tt\"\u003eniwel\u003c/span\u003e\".\u003c/p\u003e\u003cp\u003eYou found two strings \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ex\u003c/i\u003e\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ey\u003c/i\u003e\u003c/span\u003e of the same length and consisting of only lowercase English letters. Find any string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e such that \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003ci\u003ex\u003c/i\u003e, \u003ci\u003ez\u003c/i\u003e) \u003d \u003ci\u003ey\u003c/i\u003e\u003c/span\u003e, or print \u003cspan class\u003d\"tex-font-style-tt\"\u003e-1\u003c/span\u003e if no such string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e exists.\u003c/p\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003eThe first line of input contains the string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ex\u003c/i\u003e\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe second line of input contains the string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ey\u003c/i\u003e\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eBoth \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ex\u003c/i\u003e\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ey\u003c/i\u003e\u003c/span\u003e consist only of lowercase English letters, \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ex\u003c/i\u003e\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ey\u003c/i\u003e\u003c/span\u003e have same length and this length is between \u003cspan class\u003d\"tex-span\"\u003e1\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e100\u003c/span\u003e.\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003eIf there is no string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e such that \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003ci\u003ex\u003c/i\u003e, \u003ci\u003ez\u003c/i\u003e) \u003d \u003ci\u003ey\u003c/i\u003e\u003c/span\u003e, print \u003cspan class\u003d\"tex-font-style-tt\"\u003e-1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eOtherwise, print a string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e such that \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003ci\u003ex\u003c/i\u003e, \u003ci\u003ez\u003c/i\u003e) \u003d \u003ci\u003ey\u003c/i\u003e\u003c/span\u003e. If there are multiple possible answers, print any of them. The string \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e should be the same length as \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ex\u003c/i\u003e\u003c/span\u003e and \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ey\u003c/i\u003e\u003c/span\u003e and consist only of lowercase English letters.\u003c/p\u003e"}},{"title":"Examples","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003eab\naa\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eba\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003enzwzl\nniwel\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003exiyez\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003eab\nba\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e-1\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"Note","value":{"format":"HTML","content":"\u003cp\u003eThe first case is from the statement.\u003c/p\u003e\u003cp\u003eAnother solution for the second case is \"\u003cspan class\u003d\"tex-font-style-tt\"\u003ezizez\u003c/span\u003e\"\u003c/p\u003e\u003cp\u003eThere is no solution for the third case. That is, there is no \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e\u003c/span\u003e such that \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ef\u003c/i\u003e(\u003c/span\u003e\"\u003cspan class\u003d\"tex-font-style-tt\"\u003eab\u003c/span\u003e\", \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ez\u003c/i\u003e) \u003d \u003c/span\u003e \"\u003cspan class\u003d\"tex-font-style-tt\"\u003eba\u003c/span\u003e\".\u003c/p\u003e"}}]}