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#include<cmath>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define forU(i, a, b) for (int i = (a), UP = (b); i <= UP; ++i)
#define forD(i, a, b) for (int i = (a), DOWN = (b); i >= DOWN; --i)
using namespace std;

inline double fabs(double x) {return x < 0 ? -x : x;}

const int N = 55;
const int M = N * N * 2;

struct node {
    int nxt, to; double c;
    node(int _nxt = 0, int _to = 0, double _c = 0) : nxt(_nxt), to(_to), c(_c) {}
} E[M];
int cnt, point[N << 1], cur[N << 1];

void ins(int u, int v, double c) {
    E[++cnt] = node(point[u], v, c); point[u] = cnt;
    E[++cnt] = node(point[v], u, 0); point[v] = cnt;
}

bool can[N][N];
int q[N << 1], n, m, S, T, d[N << 1];
double A[N], B[N];

bool BFS() {
    memset(d, 0, sizeof(int) * (T + 1));
    int head = 0, tail = 1, u, v; q[1] = S; d[S] = 1;
    while (head != tail) {
        u = q[++head];
        for (int i = point[u]; i; i = E[i].nxt)
            if (fabs(E[i].c) > 1e-12 && !d[v = E[i].to]) {
                d[v] = d[u] + 1;
                q[++tail] = v;
            }
    }
    return d[T];
}

double DFS(int u, double a) {
    if (fabs(a) < 1e-12 || u == T) return a;
    double f, flow = 0;
    for (int &i = cur[u]; i; i = E[i].nxt)
        if (d[E[i].to] == d[u] + 1 && fabs(f = DFS(E[i].to, min(a, E[i].c))) > 1e-12) {
            a -= f; flow += f; E[i].c -= f; E[i ^ 1].c += f;
            if (fabs(a) < 1e-12) break;
        }
    return flow;
}

double Dinic() {
    double flow = 0;
    while (BFS()) {
        memcpy(cur, point, sizeof(int) * (T + 1));
        flow += DFS(S, 100000000000000.0);
    }
    return flow;
}

double tot = 0;

bool can2(double tim) {
    memset(point, 0, sizeof(int) * (T + 1));
    cnt = 1;
    forU (i, 1, m) {
        ins(S, i, tim * B[i]);
        forU (j, 1, n)
            if (can[i][j])
                ins(i, j + m, 100000000000000.0);
    }
    forU (i, 1, n) ins(i + m, T, A[i]);
    
    return fabs(Dinic() - tot) < 1e-5;
}

int main() {
    scanf("%d%d", &n, &m); S = n + m + 1; T = S + 1;
    forU (i, 1, n) scanf("%lf", A + i), tot += A[i];
    forU (i, 1, m) scanf("%lf", B + i);
    int num;
    double left = 0, right = 0, mid;
    forU (i, 1, m)
        forU (j, 1, n) {
            scanf("%d", &num);
            can[i][j] = num;
        }
    forU (i, 1, n) {
        double fornow = 0;
        forU (j, 1, m)
            fornow = max(fornow, B[j]);
        right += ceil(A[i] / fornow);
    }
    
    while (right - left > 1e-5) {
        mid = (left + right) / 2.0;
        if (can2(mid)) right = mid;
        else left = mid;
    }
    
    printf("%.3lf\n", left);
    return 0;
}