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