#include <stdio.h>

int main() {
    int a = 0, b = 0;
    scanf("%d %d", &a, &b);
    int result = 0;
    for (int i = a; i <= b; i++) {
        int get = i;
        int sum = 0;
        for (int j = 0; get >= 1; j++) {
            sum += get % 10;
            get /= 10;
        }
        if (sum % 5 == 0) result++;
    }
    printf("%d", result);
    return 0;
}