#include <bits/stdc++.h>
using namespace std;

int main()
{
int i;
int j;
int A[] = { 2, 3, 5, 7, 11, 13 };
int B[] = { 4, 6, 8, 9, 10, 12 };
int K;
int iCnt;

	cin >> K;

	iCnt = 0;
	for( i = 0; i < 6; i++ )
	{
		for( j = 0; j < 6; j++ )
		{
			if( K == A[ i ] * B[ j ] ) iCnt++;
		}
	}

	cout << (long double) iCnt / 36 << endl;

	return 0;
}