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