知识点:

函数:函数

#include <iostream>
using namespace std;

int fun(int n);

int main() {
    int a, b;
    cin >> a >> b;
    int res = 0;

    for (int i = a; i <= b; i++) {
        if (fun(i) % 5 == 0) {
            res++;
        }
    }

    cout << res;

    return 0;
}

int fun(int n) {
    int sum = 0;

    while (n > 0) {
        sum += n % 10;
        n /= 10;
    }

    return sum;
}