[{"sectionTitle":"题目描述","type":"Text","text":"原题来自：NEERC 2000 Central Subregional，题面详见 Ural 1057。\r\n\r\n求给定区间 $[X,Y]$ 中满足下列条件的整数个数：这个数恰好等于 $K$ 个互不相等的 $B$ 的整数次幂之和。例如，设 $X=15,Y=20,K=2,B=2$，则有且仅有下列三个数满足题意：\r\n$$\r\n\begin{align}\r\n17&=2^4+2^0 \\ 18&=2^4+2^1 \\ 20&=2^4+2^2\r\n\end{align}\r\n$$","subType":"markdown"},{"sectionTitle":"输入格式","type":"Text","text":"第一行包含两个整数 $X$ 和 $Y$，接下来两行包含整数 $K$ 和 $B$。","subType":"markdown"},{"sectionTitle":"输出格式","type":"Text","text":"只包含一个整数，表示满足条件的数的个数。","subType":"markdown"},{"sectionTitle":"样例","type":"Sample","text":"","subType":"markdown","payload":["15 20\n2\n2","3"]},{"sectionTitle":"数据范围与提示","type":"Text","text":"对于全部数据，$1\\le X\\le Y\\le 2^{31}-1,1\\le K\\le 20,2\\le B\\le 10$。","subType":"markdown"}]