#include <iostream>

using namespace std;

// 求每位之和
int PlaceSum(int i)
{
    int sum = 0;
    while (i != 0) {
        sum += i % 10;
        i = i / 10;
    }
    return sum;
}

int main()
{
    int x;
    int y;
    cin >> x >> y;
    int count = 0;
    for (int i = x; i <= y; i++) {
        int sum = PlaceSum(i);
        // 判断是否为5的倍数
        if (sum % 5 == 0) {
            count++;
        }
    }
    cout << count;
    return 0;
}