#include<cstdio>

#include<cstring>

#include<cmath>

#include<queue>

using namespace std;

#define N 51

#define EPS 0.000001

#define INF 2147483647.0

typedef double db;

queue<int>q;

int n,m,a[N],b[N],sumv;

bool can[N][N];

int v[2*N*(N+1)],en,first[N*2+3],next[2*N*(N+1)];

db cap[2*N*(N+1)];

void AddEdge(int U,int V,db W)

{

    v[en]=V; cap[en]=W; next[en]=first[U]; first[U]=en++;

    v[en]=U; cap[en]=0; next[en]=first[V]; first[V]=en++;

}

int S,T,nn;

int d[N*2+3],cur[N*2+3];

bool bfs()

{

    memset(d,-1,sizeof(int)*(nn+1));

    d[S]=0;

    q.push(S);

    while(!q.empty())

      {

        int U=q.front(); q.pop();

        for(int i=first[U];i!=-1;i=next[i])

          if(d[v[i]]==-1&&cap[i]>EPS)

            {

              d[v[i]]=d[U]+1;

              q.push(v[i]);

            }

      }

    return d[T]!=-1;

}

db dfs(int U,db a)

{

    if(U==T||a<=EPS)

      return a;

    db Flow=0.0,f;

    for(int &i=cur[U];i!=-1;i=next[i])

      if(d[v[i]]==d[U]+1&&(f=dfs(v[i],min(a,cap[i])))>EPS)

        {

          cap[i]-=f;

          cap[i^1]+=f;

          Flow+=f;

          a-=f;

          if(a<=EPS)

            break;

        }

    if(Flow<=EPS) d[U]=-1;

    return Flow;

}

db MaxFlow()

{

    db Flow=0.0,tmp;

    while(bfs())

      {

        memcpy(cur,first,sizeof(int)*(nn+1));

        while((tmp=dfs(S,INF))>EPS) Flow+=tmp;

      }

    return Flow;

}

bool check(db Lim)

{

    memset(first,-1,sizeof(int)*(nn+1));

    en=0;

    for(int i=1;i<=m;++i)

      AddEdge(S,1+i,Lim*(db)b[i]);

    for(int i=1;i<=n;++i)

      AddEdge(1+m+i,T,(db)a[i]);

    for(int i=1;i<=m;++i)

      for(int j=1;j<=n;++j)

        if(can[i][j])

          AddEdge(1+i,1+m+j,INF);

    return fabs(MaxFlow()-(db)sumv)<=EPS?1:0;

}

int main()

{

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

    for(int i=1;i<=n;++i)

      {

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

        sumv+=a[i];

      }

    for(int i=1;i<=m;++i) scanf("%d",&b[i]);

    for(int i=1;i<=m;++i)

      for(int j=1;j<=n;++j)

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

    S=1; T=nn=m+n+2;

    db l=0.0,r=5000000.0;

    while(r-l>EPS)

      {

        db mid=(l+r)/2.0;

        if(check(mid))

          r=mid-EPS;

        else

          l=mid+EPS;

      }

    printf("%lf\n",l);

    return 0;

}