#include <bits/stdc++.h>

#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define F first
#define S second
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

int main() {
  // ios_base::sync_with_stdio(false);
  int T, N;
  cin >> T >> N;
  vector<int> c(N);
  vector<vector<int>> v(N);
  rep(i, N) cin >> c[i];
  rep(i, N) {
    int tmp;
    cin >> tmp;
    while(tmp) {
      v[i].push_back(tmp);
      tmp /= 2;
    }
  }
  vector<int> dp(T + 1, -1);
  dp[0] = 0;
  for(int j = 0; j < N; j++) {
    for(int k = 0; k < v[j].size(); k++) {
      for(int i = T; i >= 0; i--) {
        if(dp[i] == -1 || i + c[j] > T) continue;
        dp[i + c[j]] = max(dp[i + c[j]], dp[i] + v[j][k]);
      }
    }
  }
  int ans = 0;
  rep(i, T + 1) ans = max(ans, dp[i]);    
  cout << ans << endl;
  return 0;
}