#include <bits/stdc++.h>
using namespace std;
double EPS = 1e-9;
int INF = 1000000000;
long long INFF = 8000000000000000000LL;
double PI = acos(-1);
int dirx[8] = {-1, 0, 0, 1, -1, -1, 1, 1};
int diry[8] = {0, 1, -1, 0, -1, 1, -1, 1};
inline string IntToString(int a) {
  char x[100];
  sprintf(x, "%d", a);
  string s = x;
  return s;
}
inline int StringToInt(string a) {
  char x[100];
  int res;
  strcpy(x, a.c_str());
  sscanf(x, "%d", &res);
  return res;
}
inline string GetString(void) {
  char x[1000005];
  scanf("%s", x);
  string s = x;
  return s;
}
inline string uppercase(string s) {
  int n = (int)s.size();
  for (int(i) = (0); (i) < (n); ++(i))
    if (s[i] >= 'a' && s[i] <= 'z') s[i] = s[i] - 'a' + 'A';
  return s;
}
inline string lowercase(string s) {
  int n = (int)s.size();
  for (int(i) = (0); (i) < (n); ++(i))
    if (s[i] >= 'A' && s[i] <= 'Z') s[i] = s[i] - 'A' + 'a';
  return s;
}
inline void OPEN(string s) {
  freopen((s + ".in").c_str(), "r", stdin);
  freopen((s + ".out").c_str(), "w", stdout);
}
int k, n1, n2, n3, t1, t2, t3;
priority_queue<int, vector<int>, greater<int> > satu, dua, tiga;
int t[100005];
bool can(int T) {
  if ((int)satu.size() == n1 && satu.top() + t1 > T) return false;
  if ((int)dua.size() == n2 && dua.top() + t2 > T + t1) return false;
  if ((int)tiga.size() == n3 && tiga.top() + t3 > T + t1 + t2) return false;
  return true;
}
int main() {
  scanf("%d %d %d %d %d %d %d", &k, &n1, &n2, &n3, &t1, &t2, &t3);
  int bef = 0;
  for (int(i) = (0); (i) < (k); ++(i)) {
    int ambil = bef;
    int L = t[i - 1];
    int R = INF;
    while (L <= R) {
      int M = (L + R) >> 1;
      if (can(M)) {
        ambil = M;
        R = M - 1;
      } else
        L = M + 1;
    }
    if ((int)satu.size() == n1) {
      satu.pop();
    }
    satu.push(ambil);
    if ((int)dua.size() == n2) {
      dua.pop();
    }
    dua.push(ambil + t1);
    if ((int)tiga.size() == n3) {
      tiga.pop();
    }
    tiga.push(ambil + t1 + t2);
    if (i == k - 1) {
      printf("%d\n", ambil + t1 + t2 + t3);
    }
    bef = ambil;
  }
  return 0;
}
