#include <stdio.h>
int sum,count=0;
int count1(int n)
    {   
        sum=0;
        while(n>0)
        {
            sum=sum+n%10;
            n=n/10;
        }
        if(sum%5==0)
        {
            count++;
        }
        return count;
    }
int main() {
    int a,b,i=0;
    scanf("%d %d",&a,&b);
    for(i=a;i<=b;i++)
    {
        count1(i);
    }
    printf("%d",count);
    return 0;

}