#include <stdio.h>

int main(void) {
	// your code goes here
	int sosuu[6] = {2, 3, 5, 7, 11, 13};
	int gousei[6] = {4, 6, 8, 9, 10, 12};
	int seki[6][6];
	int i,j,k;
	double ans = 0.0;
	
	for(i = 0; i < 6; i++){
		for(j = 0; j < 6; j++){
			seki[i][j] = sosuu[i] * gousei[j];
		}
	}
	
	fscanf(stdin, "%d", &k);
	
	for(i = 0; i < 6; i++){
		for(j = 0; j < 6; j++){
			if(seki[i][j] == k){
				ans += 1.0;
			}
		}
	}
	
	if(ans != 0.0){
		ans /= 36.0;
	}
	
	printf("%.17f", ans);
	
	
	return 0;
}