LG3317

#include<bits/stdc++.h>

using namespace std;

#define gc c=getchar()
#define r(x) read(x)
#define db double

template<typename T>
inline void read(T&x){
    T k=1;char gc;x=0;
    while(!isdigit(c)){if(c=='-')k=-1;gc;}
    while(isdigit(c))x=x*10+c-'0',gc;x*=k;
}

const int N=55;
const db eps=1e-8;

inline int dcmp(const db &a){
    return (fabs(a)<eps)?0:(a>0?1:-1);
}

long db G[N][N];

inline db det(int n){
    db ret=1;
    for(int i=1;i<=n;++i){
        int mx=i;
        for(int j=i+1;j<=n;++j){
            if(dcmp(G[j][i]-G[mx][i])>0)mx=j;
        }
        for(int j=1;j<=n;++j){
            swap(G[i][j],G[mx][j]);
        }
        for(int j=i+1;j<=n;++j){
            db t=G[j][i]/G[i][i];
            for(int k=1;k<=n;++k){
                G[j][k]-=G[i][k]*t;
            }
        }
        ret*=G[i][i];
    }
    return fabs(ret);
}

int main(){
    // freopen(".in","r",stdin);
    // freopen(".out","w",stdout);
    int n;r(n);
    db tmp=1;
    for(int i=1;i<=n;++i){
        for(int j=1;j<=n;++j){
            db x,y;scanf("%lf",&x);
            if(i==j)continue;
            if(x==1)x=1-eps;
            y=1-x;
            G[i][j]=-x/y;
            if(i<j)tmp*=y;
            G[i][i]-=G[i][j];
        }
    }
    printf("%.5lf\n",det(n-1)*tmp);
}