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

typedef long long ll;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef vector< ll > vl;
typedef vector< vl > vvl;
typedef pair< int, int > pii;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int N;

void init(){
  cin >> N;
}

void preprocess(){
  
}

double comb( int n, int m ){
  double res = 1.0;
  for( int i = m + 1; i <= n; ++i )
    res *= i;
  for( int i = n - m + 1; i <= n; ++i )
    res /= i;
  return res;
}

void solve(){
  cout << fixed << setprecision( 9 ) << 12.0 * comb( N, 5 ) / comb( 99, 5 ) << endl;
}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}