{"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":"HTML","content":"一个A和两个B一共可以组成三种字符串:\"ABB\"、\"BAB\"、\"BBA\"。\u003cbr\u003e\n给定若干字母和它们相应的个数,计算一共可以组成多少个不同的字符串。\n"}},{"title":"输入","value":{"format":"HTML","content":"每组测试数据分两行,第一行为n (1\u003c\u003dn\u003c\u003d26),表示不同字母的个数;第二行为n个数a1、a2、...、an(1\u003c\u003dai\u003c\u003d12),表示每种字母的个数。测试数据以n\u003d0为结束。\n\u003cbr\u003e"}},{"title":"输出","value":{"format":"HTML","content":"对于每一组测试数据,输出一个m,表示一共有多少种字符串。\n\u003cbr\u003e"}},{"title":"输入样例","value":{"format":"HTML","content":"\u003cpre\u003e2\n1 2\n3\n2 2 2\n0\u003c/pre\u003e"}},{"title":"输出样例","value":{"format":"HTML","content":"\u003cpre\u003e3\n90\u003c/pre\u003e"}}]}