// luogu-judger-enable-o2
#include<cstdio>
#include<iostream>
#include<cstring>
#include<vector>
#include<queue>
#define ri register int
#define N 505
#define INF 1000000007
#define T (n+m+1)
#define eps 1e-5using namespace std;int n,m;
vector<int> to,ed[N];
vector<double> w;
int cur[N],d[N];
double sum;
int g[N][N],a[N],b[N];inline int read() {int f=0,ret=0; char ch=getchar();while (ch<'0' || ch>'9') f|=(ch=='-'),ch=getchar();while (ch>='0'&&ch<='9') ret*=10,ret+=(ch-'0'),ch=getchar();return f?-ret:ret;
}void add_edge(int u,int v,double w1,double w2) {to.push_back(v); w.push_back(w1); ed[u].push_back(to.size()-1);to.push_back(u); w.push_back(w2); ed[v].push_back(to.size()-1);
}bool bfs() {queue<int> q;memset(d,0x3f,sizeof(d));d[0]=0; q.push(0);while (!q.empty()) {int x=q.front(); q.pop();for (ri i=0,l=ed[x].size();i<l;i++) {int e=ed[x][i];if (w[e]>eps && d[x]+1<d[to[e]]) {d[to[e]]=d[x]+1;q.push(to[e]);}}}return d[T]<=1000000;
}double dfs(int x,double limit) {if (x==T || !limit) return limit;double tot=0;for (ri &i=cur[x];i<ed[x].size();i++) {int e=ed[x][i];if (d[to[e]]==d[x]+1 && w[e]>eps) {double f=dfs(to[e],min(limit,w[e]));if (f<eps) continue;w[e]-=f; w[1^e]+=f; tot+=f; limit-=f;if (limit<eps) return tot;}}return tot;
}double dinic() {double ret=0;while (bfs()) {memset(cur,0,sizeof(cur));ret+=dfs(0,INF);}return ret;
}bool check(double t) {w.clear(); to.clear();for (ri i=0;i<=n+m+1;i++) ed[i].clear();for (ri i=1;i<=m;i++) add_edge(0,i,t*b[i],0);for (ri i=1;i<=n;i++) add_edge(m+i,T,a[i],0);for (ri i=1;i<=m;i++)for (ri j=1;j<=n;j++) if (g[i][j]) add_edge(i,m+j,INF,0);if (dinic()+eps>sum) return 1; else return 0;
}int main() {n=read(); m=read();for (ri i=1;i<=n;i++) a[i]=read();sum=0.0;for (ri i=1;i<=n;i++) sum+=a[i];for (ri i=1;i<=m;i++) b[i]=read();for (ri i=1;i<=m;i++)for (ri j=1;j<=n;j++) g[i][j]=read();double lb=0,rb=10007; double ans=-1;while (rb-lb>1e-4) {double mid=(lb+rb)/2;if (check(mid)) ans=mid,rb=mid; else lb=mid;}printf("%.4lf",ans);return 0;
}