#include<bits/stdc++.h>
using namespace std;
#define N 510
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const ll inf = 1e15;struct edge
{int to;ll w;int nxt;
} e[N * N * 5];int n , m , tot , S , T;
int dep[N] , head[N] , g[N][N];
ll a[N] , b[N];template <typename T> inline void chkmax(T &x,T y) { x = max(x,y); }
template <typename T> inline void chkmin(T &x,T y) { x = min(x,y); }
template <typename T> inline void read(T &x)
{T f = 1; x = 0;char c = getchar();for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - '0';x *= f;
}
inline void addedge(int u , int v , ll w)
{++tot;e[tot] = (edge){v , w , head[u]};head[u] = tot;++tot;e[tot] = (edge){u , 0 , head[v]};head[v] = tot;
}
inline bool bfs()
{queue< int > q;for (int i = 1; i <= T; ++i)dep[i] = -1;q.push(S);dep[S] = 1;while (!q.empty()){int cur = q.front();q.pop();for (int i = head[cur]; i; i = e[i].nxt){int v = e[i].to;ll w = e[i].w;if (w > 0 && dep[v] == -1){dep[v] = dep[cur] + 1;q.push(v);if (v == T) return true;}}}return false;
}
inline ll dinic(int u , ll flow)
{ll k , rest = flow;if (u == T)return flow;for (int i = head[u]; i && rest; i = e[i].nxt){int v = e[i].to;ll w = e[i].w;if (dep[v] == dep[u] + 1 && w){k = dinic(v , min(w , rest));e[i].w -= k;e[i ^ 1].w += k;if (!k) dep[v] = 0;rest -= k;}}return flow - rest;
}
inline bool check(ll mid)
{S = n + m + 1 , T = S + 1;for (int i = 1; i <= T; ++i) head[i] = 0;for (int i = 1; i <= tot; ++i) e[i].nxt = 0;tot = 1;for (int i = 1; i <= m; ++i) addedge(S , i , b[i] * mid);for (int i = 1; i <= m; ++i){for (int j = 1; j <= n; ++j){if (g[i][j])addedge(i , j + m , inf);}}ll sum = 0;for (int i = 1; i <= n; ++i) {addedge(i + m , T , a[i]);sum += a[i];}ll res = 0;while (bfs()){while (double flow = dinic(S , inf)) res += flow;}return res == sum;
}int main()
{scanf("%d%d" , &n , &m); for (int i = 1; i <= n; ++i) {scanf("%lld" , &a[i]);a[i] *= 1000;}for (int i = 1; i <= m; ++i) scanf("%lld" , &b[i]);for (int i = 1; i <= m; ++i){for (int j = 1; j <= n; ++j){scanf("%d" , &g[i][j]);}}ll l = 0 , r = inf , ans = 0;while (l <= r){int mid = (l + r) >> 1;if (check(mid)){ans = mid;r = mid - 1;} else l = mid + 1;}printf("%.6lf\n" , (double)(ans / 1000.0));return 0;}