#include <bits/stdc++.h>
int main() {
  int a, b, c;
  scanf("%d%d%d", &a, &b, &c);
  for (int i = 1; i <= 300; i++) {
    if (i <= a && i * 2 <= b && i * 4 <= c) continue;
    if (i - 1 == 0)
      printf("0\n");
    else
      printf("%d\n", i - 1 + (i - 1) * 2 + (i - 1) * 4);
    break;
  }
  return 0;
}
