#include <bits/stdc++.h>
int main() {
  int a, b, c, x, y, z, s;
  scanf("%d %d %d", &a, &b, &c);
  a = a;
  b = b / 2;
  c = c / 4;
  if (a <= b && a <= c) {
    x = a;
    y = x * 2;
    z = x * 4;
  } else if (b <= a && b <= c) {
    x = b;
    y = x * 2;
    z = x * 4;
  } else {
    x = c;
    y = x * 2;
    z = x * 4;
  }
  s = x + y + z;
  printf("%d\n", s);
  return 0;
}
