#include <stdio.h>

int main(){
	int a[6]={2,3,5,7,11,13};
	int b[6]={4,6,8,9,10,12};
	int n=0,k;
	int i,j;
	double ans;
	scanf("%d",&k);
	for(i=0; i<6; i++){
		for(j=0; j<6; j++){
			if(a[i]*b[j]==k)n++;
		}
	}
	ans=(double)n/36;
	printf("%.17lf\n",ans);
	return 0;
}