#include <stdio.h>

int main(void){
	long long int n,h,J,K,ans=0;
	long long int th, y = 2014, m = 7, d = 23;
	J = y/100;
	K = y%100;
	h = (d + ((m+1)*26/10) + K + (K/4) + (J/4) + 5*J)%7;
	
	scanf("%lld", &n);
	
	for(y=2015;y<=n;y++){
		J = y/100;
		K = y%100;
		th = (d + ((m+1)*26/10) + K + (K/4) + (J/4) + 5*J)%7;
		if(h == th){
			ans++;
		}
	}
	printf("%lld\n", ans);
	
	return 0;
}