[{"sectionTitle":"题目描述","type":"Text","text":"原题来自：CTU Open 2004\r\n\r\n对于 C 语言的\r\nc\r\nfor (variable = A; variable != B; variable += C)\r\n statement;\r\n\r\n循环语句，问在 $k$ 位存储系统中循环几次才会结束。若在有限次内结束，则输出循环次数。否则输出死循环。","subType":"markdown"},{"sectionTitle":"输入格式","type":"Text","text":"多组数据，每组数据一行四个整数 $A, B, C, k$。$k$ 表示 $k$ 位存储系统。\r\n\r\n读入以 0 0 0 0 结束。","subType":"markdown"},{"sectionTitle":"输出格式","type":"Text","text":"若在有限次内结束，则输出循环次数。否则输出 FOREVER。","subType":"markdown"},{"sectionTitle":"样例","type":"Sample","text":"","subType":"markdown","payload":["3 3 2 16\n3 7 2 16\n7 3 2 16\n3 4 2 16\n0 0 0 0","0\n2\n32766\nFOREVER"]},{"sectionTitle":"数据范围与提示","type":"Text","text":"对于全部数据，$1\\le k\\le 32,0\\le A,B,C\\lt 2^k$。","subType":"markdown"}]