#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, ans = 0, x = 1;
  cin >> a >> b >> c;
  while (x <= a && 2 * x <= b && x * 4 <= c) {
    ans = x + x * 2 + x * 4;
    x++;
  }
  cout << ans;
  return 0;
}
