#include <bits/stdc++.h>
#define eps 1e-6
using namespace std;
const int N = 55;
namespace mat {
double a[N][N];
int n,p=1;
double gauss_jordan() {
double ans = 1;
for(int i=1;i<=n;i++) {
int r=i;
for(int j=i+1;j<=n;j++) if(fabs(a[j][i])>fabs(a[r][i])) r=j;
if(r-i) {for(int j=1;j<=n+1;j++) swap(a[i][j],a[r][j]); ans*=-1;}
//if(fabs(a[i][i])<eps) {p=0; return;}
for(int j=1;j<=n;j++) if(j-i) {
double tmp=a[j][i]/a[i][i];
for(int k=i+1;k<=n+1;k++) a[j][k]-=a[i][k]*tmp;
}
ans*=a[i][i];
}
return ans;
}
} // namespace mat
double n,p[N][N];
int main() {
cin>>n;
for(int i=1;i<=n;i++) {
for(int j=1;j<=n;j++) {
cin>>p[i][j];
if(abs(1-p[i][j])<eps) p[i][j]-=eps;
}
}
double ans=1;
for(int i=1;i<=n;i++) {
for(int j=i+1;j<=n;j++) {
ans*=1-p[i][j];
}
}
for(int i=1;i<=n;i++) {
for(int j=1;j<=n;j++) if(i!=j) {
mat::a[i][j]=-p[i][j]/(1-p[i][j]);
mat::a[i][i]+=p[i][j]/(1-p[i][j]);
}
}
mat::n=n-1;
ans*=mat::gauss_jordan();
printf("%.8lf
",ans);
}