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

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