#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int t, n;
vector<int> c, v;
vector< vector<int> > dp;

int solve(int _n, int _t) {
  if (_n < 0) return 0;
  if (dp[_n][_t] != -1) return dp[_n][_t];

  int ret = -1;
  if (_t - c[_n] >= 0) ret = max(ret, solve(_n - 1, _t - c[_n]) + v[_n]);
  ret = max(ret, solve(_n - 1, _t));
  return dp[_n][_t] = ret;
}

int main(void) {
  cin >> t >> n;
  
  c.assign(n, 0);
  v.assign(n, 0);
  
  for (int i = 0; i < n; i++) cin >> c[i];
  for (int i = 0; i < n; i++) cin >> v[i];

  for (int i = 0; i < n; i++) {
    int _v = v[i];
    while (true) {
      _v = _v / 2;
      if (_v == 0) break;
      v.push_back(_v);
      c.push_back(c[i]);
    }
  }

  dp.assign(c.size(), vector<int>(t + 1, -1));
  cout << solve(c.size() - 1, t) << endl;

  return 0;
}