#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;

typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound

#define sz(x) (int)x.size()
#define beg(x) x.begin()
#define en(x) x.end()
#define all(x) beg(x), en(x)
#define resz resize

const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
const ld PI = 4*atan((ld)1);

template<class T> void ckmin(T &a, T b) { a = min(a, b); }
template<class T> void ckmax(T &a, T b) { a = max(a, b); }

int N, M, perm [10];
ll arr [100010], groups [10], lo = 0, hi = INF/10000ll, ret;

bool checkLess(ll p, ll q, ll r){
	return p/q < r || (p/q == r && p%q == 0);
}

bool checkIt(ll mini){
	for(int i = 0; i < M; i++) perm[i] = i;
	map<pair<int, int>, int> nexts;
	do{
		int idx = 0;
		for(int i = 0; i < M; i++){
			int curr = perm[i];
			if(nexts.find(mp(idx, curr)) == nexts.end()){
			    int a = idx, b = N, best;
    			while(a <= b){
    				int mid = (a+b)/2;
    				if(checkLess(arr[mid]-arr[idx], groups[curr], mini)){ a = mid+1; best = mid; }
    				else b = mid-1;
    			}
    			nexts[mp(idx, curr)] = best;
		    }
			idx = nexts[mp(idx, curr)];
			if(idx == N) break;
		}
		if(idx == N) return true;
	}while(next_permutation(perm, perm+M));
	return false;
}

int main() {
    // you should actually read the stuff at the bottom
    ios_base::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(10);
    cin >> N >> M;
	 for(int i = 1; i <= N; i++){
	 		cin >> arr[i];
			arr[i] += arr[i-1];
	 }
	 for(int i = 0; i < M; i++) cin >> groups[i];
	 while(lo <= hi){
	 	ll mid = (lo+hi)/2;
		if(checkIt(mid)){ hi = mid-1; ret = mid; }
		else lo = mid+1;
	 }
	 cout << ret << '\n';
	 //cout << "HI" << endl;
    // you should actually read the stuff at the bottom
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?), set tle
    * do smth instead of nothing and stay organized