#include<bits/stdc++.h>
#define ll long long
#define sz(a) ((int) (a).size())
#define vi vector < int >
#define pb emplace_back
using namespace std;
#define db double
const db eps = 1e-7;
int n;
db a[110][110], ans = 1;
double det(int n) {
  cout << fixed << setprecision(5);
//  cout << "Matrix A: \n";
//  for(int i = 1; i <= n; ++i, cout << "\n") 
//    for(int j = 1; j <= n; ++j)
//      cout << a[i][j] << " ";
  int coef = 0;
  for(int i = 1; i <= n; ++i) {
    int p = i;
    for(int j = 1; j <= n; ++j)
      if(fabs(a[j][i]) > fabs(a[p][i]))
        p = j;
    if(i ^ p)
      swap(a[i], a[p]), coef ^= 1;
    if(fabs(a[i][i]) < eps)
      cout << "?\n", exit(0);
    for(int j = i + 1; j <= n; ++j)
      if(i != j && fabs(a[j][i]) > eps) {
        db t = a[j][i] / a[i][i];
        for(int k = n; k >= i; --k)
          a[j][k] -= t * a[i][k];
      }
  }
  db ret = 1;
  for(int i = 1; i <= n; ++i)
    ret *= a[i][i];
  return !coef ? ret : -ret;
}
int main() {
  ios :: sync_with_stdio(false);
  cin.tie(0); cout.tie(0);
  cin >> n;
  for(int i = 1; i <= n; ++i)
    for(int j = 1; j <= n; ++j) {
      cin >> a[i][j];
      if(i < j)
        ans *= (1 - a[i][j]);
      if(fabs(1 - a[i][j]) < eps)
        a[i][j] = 1 - eps;
      else
        a[i][j] = a[i][j] / (1 - a[i][j]);
    }
  for(int i = 1; i <= n; ++i) {
    a[i][i] = 0;
    for(int j = 1; j <= n; ++j)
      if(i ^ j)
        a[i][i] += a[i][j], a[i][j] *= -1;
  }
  ans *= det(n - 1);
  cout << ans << "\n";
  return 0;
}