{"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":"X和Y在进行射击比赛,X先射,它击中靶子的概率是a/b,而Y击中的概率是c/d.谁先射中谁赢。\u003cbr\u003e\n求x赢的概率."}},{"title":"Input","value":{"format":"HTML","content":"第一行4个整数,a,b,c,d;\u003cbr\u003e\n(1\u003c\u003da,b,c,d\u003c\u003d1000)\u003cbr\u003e\n(0\u003c a/b \u003c1,0\u003c c/d \u003c1)"}},{"title":"Output","value":{"format":"HTML","content":"输出一个整数,表示X赢的概率.\u003cbr\u003e\n你的答案和正确答案的差不超过10^(-6)才会被认为正确。"}},{"title":"Eg","value":{"format":"HTML","content":"【样例输入】\u003cbr\u003e\n3 4 3 4\u003cbr\u003e\n【样例输出】\u003cbr\u003e\n0.800000000000"}}]}