[{"sectionTitle":"题目描述","type":"Text","text":"科协里最近很流行数字游戏。某人命名了一种不降数，这种数字必须满足从左到右各位数字成小于等于的关系，如 $123$，$446$。现在大家决定玩一个游戏，指定一个整数闭区间 $[a,b]$，问这个区间内有多少个不降数。","subType":"markdown"},{"sectionTitle":"输入格式","type":"Text","text":"有多组测试数据。每组只含两个数字 $a,b$，意义如题目描述。","subType":"markdown"},{"sectionTitle":"输出格式","type":"Text","text":"每行给出一个测试数据的答案，即 $[a, b]$ 之间有多少不降数。","subType":"markdown"},{"sectionTitle":"样例","type":"Sample","text":"","subType":"markdown","payload":["1 9\n1 19","9\n18"]},{"sectionTitle":"数据范围与提示","type":"Text","text":"对于全部数据，$1\\le a\\le b\\le 2^{31}-1$。","subType":"markdown"}]