using namespace std;
#include <bits/stdc++.h>
#define BEGIN ios_base::sync_with_stdio(0);cin.tie(0);
#define END return EXIT_SUCCESS;
#define FOR(I,A,B) for(int (I)=(A);(I)<(B);++(I))
#define ALL(C) (C).begin(),(C).end()
inline void solve()
{
  int a[6]={2,3,5,7,11,13};
  int b[6]={4,6,8,9,10,12};
  double ans=0;
  int K;
  cin>>K;
  FOR(i,0,6) 
  {
    FOR(j,0,6) 
    {
      if(K==a[i]*b[j]) ans+=1.0/36;
    }
  }
  printf("%.15f\n",ans);
}
int main(int argc,char**argv)
{
	BEGIN
	solve();
	END
}