#include <algorithm>

#include  <iterator>

#include  <iostream>

#include   <cstring>

#include   <cstdlib>

#include   <iomanip>

#include    <bitset>

#include    <cctype>

#include    <cstdio>

#include    <string>

#include    <vector>

#include     <stack>

#include     <cmath>

#include     <queue>

#include      <list>

#include       <map>

#include       <set>

#include   <cassert>

/*

⊂_ヽ

　 ＼＼ Λ＿Λ  来了老弟

　　 ＼('ㅅ')

　　　 >　⌒ヽ

　　　/ 　 へ＼

　　 /　　/　＼＼

　　 ﾚ　ノ　　 ヽ_つ

　　/　/

　 /　/|

　(　(ヽ

　|　|、＼

　| 丿 ＼ ⌒)

　| |　　) /

'ノ )　　Lﾉ

*/

using namespace std;

#define lson (l , mid , rt << 1)

#define rson (mid + 1 , r , rt << 1 | 1)

#define debug(x) cerr << #x << " = " << x << "\n";

#define pb push_back

#define pq priority_queue

typedef long long ll;

typedef unsigned long long ull;

typedef long double ld;

//typedef __int128 bll;

typedef pair<ll ,ll > pll;

typedef pair<int ,int > pii;

typedef pair<int,pii> p3;

//priority_queue<int> q;//这是一个大根堆q

//priority_queue<int,vector<int>,greater<int> >q;//这是一个小根堆q

#define fi first

#define se second

//#define endl '\n'

#define boost ios::sync_with_stdio(false);cin.tie(0)

#define rep(a, b, c) for(int a = (b); a <= (c); ++ a)

#define max3(a,b,c) max(max(a,b), c);

#define min3(a,b,c) min(min(a,b), c);

const ll oo = 1ll<<;

const ll mos = 0x7FFFFFFF;  //

const ll nmos = 0x80000000;  //-2147483648

const int inf = 0x3f3f3f3f;

const ll inff = 0x3f3f3f3f3f3f3f3f; //

const int mod = 1e9;

const double esp = 1e-;

const double PI=acos(-1.0);

const double PHI=0.61803399;    //黄金分割点

const double tPHI=0.38196601;

template<typename T>

inline T read(T&x){

    x=;int f=;char ch=getchar();

    while (ch<''||ch>'') f|=(ch=='-'),ch=getchar();

    while (ch>=''&&ch<='') x=x*+ch-'',ch=getchar();

    return x=f?-x:x;

}

inline void cmax(int &x,int y){if(x<y)x=y;}

inline void cmax(ll &x,ll y){if(x<y)x=y;}

inline void cmin(int &x,int y){if(x>y)x=y;}

inline void cmin(ll &x,ll y){if(x>y)x=y;}

/*-----------------------showtime----------------------*/

            const int maxn = ;

            double mp[maxn][maxn];

            double a[maxn][maxn];

            int n;

            double Gauss(int n){

                for(int i=; i<n; i++){

                    int mx = i;

                    for(int j=i+; j<n; j++){

                        if(fabs(a[mx][i]) < fabs(a[j][i])) mx = j;

                    }

                    swap(a[i], a[mx]);

                    for(int j=i+; j<n; j++){

                        double tmp = a[j][i]/a[i][i];

                        for(int k=i+; k<n; k++)

                            a[j][k] -= a[i][k] * tmp;

                    }

                }

                double ans = ;

                for(int i=; i<n; i++) ans *= a[i][i];

                return fabs(ans);

            }

int main(){

            scanf("%d", &n);

            double tmp = ;

            for(int i=; i<=n; i++) {

                for(int j=; j<=n; j++) {

                    scanf("%lf", &mp[i][j]);

                    if(fabs(1.0 - mp[i][j]) < esp) mp[i][j] = 1.0- esp;

                    if(i < j)tmp = tmp * (1.0-mp[i][j]);

                    mp[i][j] = mp[i][j] / (1.0 - mp[i][j]);

                }

            }

            for(int i=; i<=n; i++){

                for(int j=i+; j<=n; j++){

                    a[i][j] = a[j][i] = -mp[i][j];

                    a[i][i] += mp[i][j];

                    a[j][j] += mp[i][j];

                }

            }

            printf("%.10f\n", Gauss(n) * tmp);

            return ;

}