#include <stdio.h>

int main(void){
	int i,j,k;
	int dice[220] = {0};
	int prime[] = {2,3,5,7,11,13};
	int compose[] = {4, 6, 8, 9, 10, 12};
	double ans;
	scanf("%d", &k);
	for(i=0;i<6;i++){
		for(j=0;j<6;j++){
			dice[prime[i]*compose[j]]++;
		}
	}
	
	ans = 1.0*dice[k] / 36.0;
	
	printf("%.20f\n", ans);
	
	return 0;
}