#include<stdio.h>

int main()
{
	int a,b,c,count=0;
	scanf("%d %d",&a,&b);

	if(1<=a && c<=10000 && a<=b)
	{
		for (a; a < b; a++)
		{
			if (a%d = 1)
			{
				count+=1;
			}
		}
		printf("%d\n",count);
	}
	return 0;
}