#include<cstdio>

#include<cstdlib>

#include<cctype>

#include<algorithm>

#include<cstring>

#include<queue>

#include<cmath>

#define maxn 450

#define eps 1e-7

using namespace std;

inline long long read(){

    long long num=,f=;

    char ch=getchar();

    while(!isdigit(ch)){

        if(ch=='')    f=-;

        ch=getchar();

    }

    while(isdigit(ch)){

        num=num*+ch-'';

        ch=getchar();

    }

    return num*f;

}

struct Edge{

    int from,next,to,val;

    double dis;

}edge[maxn*maxn*];

int head[maxn],num;

inline void addedge(int from,int to,int val,double dis){

    edge[++num]=(Edge){from,head[from],to,val,dis};

    head[from]=num;

}

inline void add(int from,int to,int val,double dis){

    addedge(from,to,val,dis);

    addedge(to,from,,-dis);

}

inline void clear(){    memset(head,,sizeof(head));    num=;    }

inline int count(int i){    return i&?i+:i-;    }

double dis[maxn];

int pre[maxn];

int flow[maxn];

bool vis[maxn];

int d[maxn][maxn];

int w[maxn][maxn];

int Start,End;

int n;

double spfa(){

    for(int i=Start;i<=End;++i)    dis[i]=-0x7fffffff; dis[Start]=;

    queue<int>q; q.push(Start);    memset(flow,,sizeof(flow)); flow[Start]=0x7fffffff;

    while(!q.empty()){

        int from=q.front();    q.pop();    vis[from]=;

        for(int i=head[from];i;i=edge[i].next){

            int to=edge[i].to;

            if(edge[i].val<=||dis[to]>=dis[from]+edge[i].dis)    continue;

            dis[to]=dis[from]+edge[i].dis;

            pre[to]=i;    flow[to]=min(flow[from],edge[i].val);

            if(vis[to])    continue;

            vis[to]=;    q.push(to);

        }

    }

    if(flow[End]==)    return ;

    int now=End;

    while(now!=Start){

        //printf("D");

        int i=pre[now];

        edge[i].val-=flow[End];

        edge[count(i)].val+=flow[End];

        now=edge[i].from;

    }

    return dis[End];

}

bool payflow(double lim){

    clear();

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

        add(Start,i,,);

        add(i+n,End,,);

    }

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

        for(int j=;j<=n;++j)    add(i,j+n,,1.0*d[i][j]-1.0*w[i][j]*lim);

    double ret=;

    while(){

        double now=spfa();

        if(fabs(now)<=eps)    break;

        ret+=now;

    }

    return ret>;

}

int main(){

    n=read();    End=n*+;

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

        for(int j=;j<=n;++j)    d[i][j]=read();

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

        for(int j=;j<=n;++j)    w[i][j]=read();

    double l=,r=1e4;double ans=;

    while(r-l>eps){

        double mid=(l+r)/2.0;

        if(payflow(mid)){

            ans=mid;

            l=mid;

        }

        else    r=mid;

    }

    printf("%.6lf",ans);

    return ;

}