#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 5;
void getmin(int a, int b, int c) {
  int d = min(a, min(b / 2, c / 4));
  cout << d * 1 + d * 2 + d * 4;
}
void solve() {
  int a, b, c;
  cin >> a >> b >> c;
  getmin(a, b, c);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  while (t--) solve();
}
