#include<bits/stdc++.h>

using namespace std;

#define il inline

#define lf double

#define gc getchar()

#define t(i) edge[i].to

#define n(i) edge[i].nxt

#define w(i) edge[i].wei

#define ri register int

#define rb register bool

#define rc register char

#define rp(i,x,y) for(ri i=x;i<=y;++i)

#define e(i,x) for(ri i=head[x];~i;i=n(i))

const int N=+,M=;

const lf eps=1e-,inf=1e9;

int S,T,ed_cnt=-,head[N],cur[N],a[N],b[N],dep[N],m,n;

bool d[M][M];

lf l,r=1e6,sum;

struct ed{int to,nxt;lf wei;}edge[N<<];

il int read()

{

    rc ch=gc;ri x=;rb y=;

    while(ch!='-' && (ch>'' || ch<''))ch=gc;

    if(ch=='-')ch=gc,y=;

    while(ch>='' && ch<='')x=(x<<)+(x<<)+(ch^''),ch=gc;

    return y?x:-x;

}

il void ad(ri x,ri y,lf z)

{edge[++ed_cnt]=(ed){x,head[y],z};head[y]=ed_cnt;edge[++ed_cnt]=(ed){y,head[x],(lf)};head[x]=ed_cnt;}

il bool bfs()

{

    queue<int>Q;Q.push(S);memset(dep,,sizeof(dep));dep[S]=;

    while(!Q.empty()){ri nw=Q.front();Q.pop();e(i,nw)if(w(i)-eps> && !dep[t(i)])dep[t(i)]=dep[nw]+,Q.push(t(i));}

    return dep[T];

}

il lf dfs(ri nw,lf flow)

{

    if(nw==T || !flow)return flow;lf ret=;

    for(ri &i=cur[nw];~i;i=n(i))

        if(w(i) && dep[t(i)]==dep[nw]+)

        {lf tmp=dfs(t(i),min(flow,w(i)));ret+=tmp,w(i)-=tmp;w(i^)+=tmp,flow-=tmp;}

    return ret;

}

il lf dinic(){lf ret=;while(bfs()){rp(i,S,T)cur[i]=head[i];while(lf d=dfs(S,inf))ret+=d;}return ret;}

il bool check(lf tim)

{

    ed_cnt=-;memset(head,-,sizeof(head));

    rp(i,,m)rp(j,,n)if(d[i][j])ad(j+m,i,inf);

    rp(i,,n)ad(T,i+m,a[i]);rp(i,,m)ad(i,S,b[i]*tim);

    //printf("dinic=%.6lf sum=%.1lf\n",dinic(),sum);

    return dinic()<sum;

}

int main()

{

    //freopen("3324.in","r",stdin);freopen("3324.out","w",stdout);

    n=read();m=read();S=;T=n+m+;rp(i,,n)sum+=a[i]=read();rp(i,,m)b[i]=read();rp(i,,m)rp(j,,n)d[i][j]=read();

    while(r-l>eps){lf mid=(l+r)/;if(check(mid))l=mid;else r=mid;}printf("%.6lf\n",r);

    //printf("%d",check(82));

    //check(82);

    return ;

}