#include int main( ) { int a, b, i, tot, c1, c2; scanf("%d %d", &a, &b); tot = 0; for (i = a; i <= b; i++) { c1 = i / 10; c2 = i % 10; if ((c1 + c2) % 3 == 0) tot++; } printf("%d\n", tot); return 0; } 输入:7 31 输出:_____1____