{"trustable":false,"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\u003e Li \u003cspan\u003e\u003cspan\u003e\u003cspan\u003eLaoshi\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e is a football lover. Since Christmas coming, he has a bet with his teammate Little Ming. To decide who can get the Christmas gift from Lady Rain, they\u0027re taking a match of penalties on the playground. They try to shoot the goal in turns, and Li \u003cspan\u003e\u003cspan\u003e\u003cspan\u003eLaoshi\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e shoots first. Since we know the probability of shooting the goal each time is \u003cimg align\u003d\"middle\" src\u003d\"http://7xjob4.com1.z0.glb.clouddn.com/92d975acd109ac8a66c1ec24a52a8d5f\"\u003e for Li while \u003cimg align\u003d\"middle\" src\u003d\"http://7xjob4.com1.z0.glb.clouddn.com/3ef7e92976b4fc108bdcd8fdc5067975\"\u003e for Ming, and the one who shoots in the goal first would be the winner.\u003c/p\u003e \n\u003cp\u003e Li \u003cspan\u003e\u003cspan\u003e\u003cspan\u003eLaoshi\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e is wonder about the probability that he will win the match,can you figure it out?\u003c/p\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003e A single line contains four integers \u003cimg align\u003d\"middle\" src\u003d\"http://7xjob4.com1.z0.glb.clouddn.com/b9917e3b392df8d5dea9e67460256a9e\"\u003e.\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003e Print a single real number, the probability that Li \u003cspan\u003e\u003cspan\u003e\u003cspan\u003eLaoshi\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e will win the match.\u003c/p\u003e \n\u003cp\u003e The answer will be considered correct if the absolute or relative error doesn\u0027t exceed \u003cspan\u003e10\u003csup\u003eā-ā6\u003c/sup\u003e\u003c/span\u003e.\u003c/p\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cdiv\u003e\n 1 2 1 2\n \u003c/div\u003e \n\u003c/div\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cp\u003e 0.666666666667\u003c/p\u003e"}},{"title":"Hint","value":{"format":"HTML","content":"\u003cp\u003e Just be careful!\u003c/p\u003e"}}]}