#include <bits/stdc++.h>
using namespace std;
int const maxn = (int)1e4 + 111;
int const inf = (1 << 30) - 1;
int k;
int a[4];
int t[4];
int d[maxn][4];
int first[maxn][4];
int main() {
  cin >> k;
  for (int i = 1; i <= 3; i++) cin >> a[i];
  for (int i = 1; i <= 3; i++) cin >> t[i];
  for (int j = 1; j <= 3; j++) {
    for (int i = 1; i <= k; i++) {
      int v = -1;
      for (int q = 1; q <= a[j]; q++) {
        if (v == -1 || first[q][j] < first[v][j]) {
          v = q;
        }
      }
      d[i][j] = max(d[i][j - 1], first[v][j]) + t[j];
      first[v][j] = d[i][j];
    }
  }
  cout << d[k][3] << endl;
  return 0;
}
