#include <stdio.h>
#include <string.h>

void Num(int a, int b)
{
	int c = 0;
	int sum = 0;
	int count = 0;
	for (int i = a; i <= b; i++)
	{
		sum = 0;
		c = i;
		while (c != 0)
		{
			sum += c % 10;
			c /= 10;
		}
		if (sum % 5 == 0)	count++;
	}
	printf("%d", count);
}
int main()
{
	int a, b;
	scanf("%d%d", &a, &b);
	Num(a, b);
	return 0;
}