#include <stdio.h>

void main(void){
	int n = 0;
	scanf("%d",&n);
	int primeDice[6] = {2,3,5,7,11,13};
	int synthesisCountDice[6] = {4,6,8,9,10,12};
	double count = 0;
	for(int i = 0;i < 6;i++){
		for(int j = 0 ; j < 6 ; j++){
			if(primeDice[i]*synthesisCountDice[j] == n){
				count++;
			}
		}
	}
	printf("%0.12f",count/36);
}