#include <bits/stdc++.h>

#define R register
#define ll long long
#define sum(a, b, mod) (((a) + (b)) % mod)
#define meow(cat...) fprintf(stderr, cat)

const double eps = 1e-7;

int n; 
double a[100][100], f[100][100];
double d[100][100], g[100][100];

int check(double x)
{
    if(x > eps) return 1;
    else if(x < -eps) return -1;
    else return 0;
}

double solve()
{
    double res = 1.0;
    // for(int i = 1; i < n; i++)
    //     for(int j = 1; j < n; j++)
    //         printf("%lf%c", a[i][j], " \n"[j == n - 1]);
    for(int i = 1; i < n; i++)
        for(int j = i + 1; j < n; j++)
        {
            while(check(a[i][i]))
            {
                double rate = a[j][i] / a[i][i];
                for(int k = i; k < n; k++)
                    a[j][k] -= rate * a[i][k];
                std::swap(a[i], a[j]), res = -res;
            }
            std::swap(a[i], a[j]), res = -res;
        }
    for(int i = 1; i < n; i++)
        res = res * a[i][i];
    return res;
}

signed main()
{   
    scanf("%d", &n);
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= n; j++)
        {
            scanf("%lf", &f[i][j]); 
            if(check(f[i][j] - 1.0) == 0) f[i][j] = 1.0 - eps;
            else if(check(f[i][j]) == 0) f[i][j] = eps;
            double r = f[i][j] / (1.0 - f[i][j]); 
            if(i <= j) continue;
            g[i][j] = g[j][i] = r, d[i][i] += r, d[j][j] += r;
        }
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= n; j++)
            a[i][j] = d[i][j] - g[i][j];
    double ans = solve();
    for(int i = 1; i <= n; i++)
        for(int j = i + 1; j <= n; j++)
            ans *= (1.0 - f[i][j]);
    printf("%lf\n", ans);
    return 0;
}