{"trustable":false,"prependHtml":"\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 async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"MD","content":"剧团要发工资咯!\n格林团长决定每个人的最低工资是888吉欧,同时有些工人希望自己的工资要比其他某个人的高。格林团长希望在尽可能的少发工资的同时满足其他所有人的需求。请你帮帮格林团长吧!"}},{"title":"Input","value":{"format":"MD","content":"题目包含多组输入\n第一行输入两个整数n,m,分别表示工人的数量与需求的个数。n不超过10000,m不超过20000.\n接下来m行,每一行都包含两个整数a和b,表示a的工资必须比b的工资高。"}},{"title":"Output","value":{"format":"MD","content":"对于每一组输入,输出格林团长最少花费的吉欧数量。\n如果格林团长不能满足所有人的需求,输出-1."}},{"title":"Sample Input","value":{"format":"MD","content":"\u003cpre\u003e2 1\n1 2\n2 2\n1 2\n2 1\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"MD","content":"\u003cpre\u003e1777\n-1\u003c/pre\u003e"}}]}