#include <bits/stdc++.h>
using namespace std;
int ts, kk = 1;
template <class T>
inline T _sq(T a) {
  return a * a;
}
template <class T, class X>
inline T _pow(T a, X y) {
  T z = 1;
  for (int i = 1; i <= y; i++) {
    z *= a;
  }
  return z;
}
template <class T>
inline T _gcd(T a, T b) {
  a = _abs(a);
  b = _abs(b);
  if (!b) return a;
  return _gcd(b, a % b);
}
template <class T>
inline T _lcm(T a, T b) {
  a = _abs(a);
  b = _abs(b);
  return (a / _gcd(a, b)) * b;
}
template <class T>
inline T _extended(T a, T b, T &x, T &y) {
  a = _abs(a);
  b = _abs(b);
  T g, x1, y1;
  if (!b) {
    x = 1;
    y = 0;
    g = a;
    return g;
  }
  g = _extended(b, a % b, x1, y1);
  x = y1;
  y = x1 - (a / b) * y1;
  return g;
}
template <class T, class X>
inline bool getbit(T a, X i) {
  T t = 1;
  return ((a & (t << i)) > 0);
}
template <class T, class X>
inline T setbit(T a, X i) {
  T t = 1;
  return (a | (t << i));
}
template <class T, class X>
inline T resetbit(T a, X i) {
  T t = 1;
  return (a & (~(t << i)));
}
template <class T, class X>
inline T togglebit(T a, X i) {
  T t = 1;
  return (a ^ (t << i));
}
template <class T, class X, class Y>
inline T _bigmod(T n, X m, Y mod) {
  unsigned long long ret = 1, a = n % mod;
  while (m) {
    if (m & 1) ret = (ret * a) % mod;
    m >>= 1;
    a = (a * a) % mod;
  }
  ret %= mod;
  return (T)ret;
}
template <class T, class Y>
inline T _modinv(T n, Y mod) {
  return _bigmod(n, mod - 2, mod);
}
queue<int> q[4];
int s[5], t[5], n[4], k;
int main() {
  cin >> k >> n[1] >> n[2] >> n[3] >> t[1] >> t[2] >> t[3];
  s[1] = k;
  s[2] = 0;
  s[3] = 0;
  s[4] = 0;
  int T = -1;
  while (s[4] != k) {
    for (int i = 1; i <= 3; i++) {
      while (!q[i].empty() && q[i].front() == T) {
        q[i].pop();
        s[i + 1]++;
      }
    }
    for (int i = 1; i <= 3; i++) {
      while (q[i].size() < n[i] && s[i]) {
        q[i].push(T + t[i]);
        s[i]--;
      }
    }
    T++;
  }
  cout << T << endl;
  return 0;
}
