#include<cstdio>

 #include<iostream>

 #include<cstdlib>

 #include<cstring>

 #define N 1008

 #define M 1000009

 #define eps 0.00001

 using namespace std;

 int S,T,A[N],B[N],f[N][N],n,m,cnt=,tot,head[N],next[M],u[M],d[N],q[N];

 double v[M],sum;

 void jia1(int a1,int a2,double a3)

 {

     cnt++;

     next[cnt]=head[a1];

     head[a1]=cnt;

     u[cnt]=a2;

     v[cnt]=a3;

     return;

 }

 void jia(int a1,int a2,double a3)

 {

     jia1(a1,a2,a3);

     jia1(a2,a1,);

     return;

 }

 bool bfs()

 {

     memset(d,,sizeof(d));

     int h=,t=;

     q[]=S;

     d[S]=;

     for(;h<t;)

       {

         h++;

         int p=q[h];

         for(int i=head[p];i;i=next[i])

           if(!d[u[i]]&&v[i])

             {

                 d[u[i]]=d[p]+;

                 if(d[T])

                   return ;

                 t++;

                 q[t]=u[i];

             }

       }

     return ;

 }

 double dinic(int s,double f)

 {

     if(s==T)

       return f;

     double rest=f;

     for(int i=head[s];i&&rest;i=next[i])

       if(v[i]&&d[u[i]]==d[s]+)

         {

             double now=dinic(u[i],min(rest,v[i]));

             if(!now)

               d[u[i]]=;

             v[i]-=now;

             v[i^]+=now;

             rest-=now;

         }

     return f-rest;

 }

 void jian(double mid)

 {

     cnt=;

     memset(head,,sizeof(head));

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

       jia(i+m,T,A[i]);

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

       jia(S,i,B[i]*mid);

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

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

         if(f[i][j])

           jia(i,j+m,);

     return;

 }

 int main()

 {

     scanf("%d%d",&n,&m);

     S=;

     T=n+m+;

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

       {

         scanf("%d",&A[i]);

         sum+=(double)A[i];

       }

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

       scanf("%d",&B[i]);

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

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

         scanf("%d",&f[i][j]);

     double l=,r=,qq;

     for(;r-l>eps;)

       {

         double mid=(l+r)/2.0;

         jian(mid);

         double ans=;

         for(;bfs();)

           ans+=dinic(S,0x7fffffff);

         if(ans>=(sum-eps))

           {

             qq=mid;

             r=mid;

           }

         else

           l=mid;

       }

     printf("%.6lf\n",qq);

     return ;

 }