#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  cin >> a >> b >> c;
  int ratiob = b / 2, ratioc = c / 4;
  if (a <= ratiob && a <= ratioc) {
    cout << a + 2 * a + 4 * a << "\n";
  } else if (ratiob <= a && ratiob <= ratioc) {
    cout << ratiob + ratiob * 2 + ratiob * 4 << "\n";
  } else if (ratioc <= a && ratioc <= ratiob) {
    cout << ratioc + ratioc * 2 + ratioc * 4 << "\n";
  }
  return 0;
}
