#include <bits/stdc++.h>
using namespace std;
bitset<100000> bt;
vector<long long int> divisor[100000];
long long int gcd(long long int a, long long int b) {
  return b == 0 ? a : gcd(b, a % b);
}
void sieve() {
  bt.set();
  bt[0] = bt[1] = 0;
  for (long long int i = 4; i <= 100000; i += 2) bt[i] = 0;
  for (long long int i = 3; i <= sqrt(100000 + 1); i += 2) {
    if (bt[i]) {
      for (long long int j = i * i; j <= 100000; j += i) bt[j] = 0;
    }
  }
}
bool isp(long long int n) {
  for (long long int i = 2; i <= sqrt(n); i++)
    if (n % i == 0) return false;
  return true;
}
void div() {
  for (long long int i = 1; i <= 100000; i++)
    for (long long int j = i; j <= 100000; j += i) divisor[j].push_back(i);
}
int main(void) {
  long int a, b, c;
  long int s = 0;
  scanf("%d", &a);
  scanf("%d", &b);
  scanf("%d", &c);
  while (a) {
    if (2 * a <= b && 4 * a <= c) {
      s = a + 2 * a + 4 * a;
      break;
    }
    a--;
  }
  printf("%ld", s);
  return 0;
}
