#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  scanf("%d%d%d", &a, &b, &c);
  int mn = min(a, min(b / 2, c / 4));
  int ans = mn + mn * 2 + mn * 4;
  printf("%d\n", ans);
  return 0;
}
