#include <bits/stdc++.h>
using namespace std;

int main() {
  int T, N;
  cin >> T >> N;
  vector<int> C(N), V(N);
  for (int i = 0; i < N; i++) cin >> C.at(i);
  for (int i = 0; i < N; i++) cin >> V.at(i);
  vector<pair<int, int>> P;
  for (int i = 0; i < N; i++) {
    int tmp = V.at(i);
    do {
      P.push_back({C.at(i), tmp});
      tmp /= 2;
    } while (tmp);
  }
  vector<long> DP(T + 1, -1);
  DP.at(0) = 0;
  for (auto [a, b] : P) {
    for (int i = T; i >= 0; i--) {
      if (DP.at(i) == -1) continue;
      if (i + a < T + 1) DP.at(i + a) = max(DP.at(i + a), DP.at(i) + b);
    }
  }
  cout << DP.at(T) << "\n";
}