#include<bits/stdc++.h>

 using namespace std;

 const int maxn =  ;

 const double eps = 1e-;

 int n;

 int a[maxn][maxn],b[maxn][maxn];

 double lx[maxn],ly[maxn],c[maxn][maxn];

 int inS[maxn],inT[maxn],Left[maxn];

 double slack[maxn];

 void read(){

     scanf("%d",&n);

     for(int i=;i<=n;i++) for(int j=;j<=n;j++) scanf("%d",&a[i][j]);

     for(int i=;i<=n;i++) for(int j=;j<=n;j++) scanf("%d",&b[i][j]);

 }

 int match(int now){

     inS[now] = ;

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

     if(inT[i]) continue;

     if(lx[now]+ly[i] - c[now][i] <= eps){

         inT[i] = ;

         if(!Left[i] || match(Left[i])){

         Left[i] = now;

         return true;

         }

     }else slack[i] = min(slack[i],lx[now]+ly[i]-c[now][i]);

     }

     return false;

 }

 void update(){

     double pp = 1e9;

     for(int i=;i<=n;i++) if(!inT[i]) pp = min(pp,slack[i]);

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

     if(inS[i]) lx[i] -= pp;

     if(inT[i]) ly[i] += pp;

     else slack[i] -= pp;

     }

 }

 bool KM(double now){

     for(int i=;i<=n;i++) for(int j=;j<=n;j++) c[i][j] = a[i][j]-now*b[i][j];

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

     lx[i] = -1E9,ly[i] = ; Left[i] = ;

     for(int j=;j<=n;j++) lx[i] = max(lx[i],c[i][j]);

     }

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

     for(int j=;j<=n;j++) slack[j] = 1e9;

     for(;;){

         for(int j=;j<=n;j++) inS[j] = inT[j] = ;

         if(match(i)) break;

         update();

     }

     }

     double ans = ;

     for(int i=;i<=n;i++) ans += lx[i] + ly[i];

     if(ans <) return false;

     else return true;

 }

 double divide(double l,double r){

     if(r-l <= eps) return l;

     double mid = (l+r)/2.0;

     int flag = KM(mid);

     if(flag) return divide(mid,r);

     else return divide(l,mid);

 }

 int main(){

     read();

     printf("%.6lf",divide(,1E4));

     return ;

 }