#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i, s, n) for (int i = (s); i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
using namespace std;
typedef long long ll;

ll N, T, K, W, H, M, C, V;
/*
const int MAX = 510000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

vector<double> cx, cy, c;
 ll MM = 1e12;

void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}*/

std::vector<int> Eratosthenes(int n ){
    std::vector<bool> is_prime( n + 1 );
    for( int i = 0; i <= n; i++ ) is_prime[ i ] = true;
    std::vector<int> P;
    for( int i = 2; i <= n; i++ ){
        if( is_prime[ i ] ){
            for( int j = 2 * i; j <= n; j += i ){
                is_prime[ j ] = false;
            }
            P.emplace_back( i );
        }
    }
    return P;
}

int main(){
    cin >> T >> N;
    vector<ll> c(N);
    vector<ll> v(N);
    REP(i, N) cin >> c[i];
    REP(i, N) cin >> v[i];
    vector<vector<ll>>  dp(N + 1, vector<ll> (T + 1, -1));
    REP(i, N + 1) dp[i][0] = 0;
    REP(i, T + 1) dp[0][i] = 0; 
    for(int i = 1; i < N+1; ++i){
        for(int t = 0; t < T + 1; ++t){
            ll cnd = dp[i-1][t];
            int num = 1;
            int vv = v[i-1];
            while(t-num*c[i-1] >= 0){
                cnd = max(cnd, dp[i-1][t-num * c[i-1]] + vv);
                vv += v[i-1]/(pow(2,num));
                ++num;
            }
            dp[i][t] = cnd;
        }
        ll m = 0;
        /*REP(t, T + 1){
             m = max(m, dp[i][t]);
             dp[i][t] = m;   
             cout << t << " " << dp[i][t] << " ";
        }
        cout << "\n";*/
    }
    cout << *max_element(ALL(dp[N]));
    return 0;
}