#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (!a) return b;
  return gcd(b % a, a);
}
long long gcdExtended(long long a, long long b, long long *x, long long *y) {
  if (a == 0) {
    *x = 0, *y = 1;
    return b;
  }
  long long x1, y1;
  long long gcd = gcdExtended(b % a, a, &x1, &y1);
  *x = y1 - (b / a) * x1;
  *y = x1;
  return gcd;
}
long long modInv(long long a, long long m) {
  long long x, y;
  long long g = gcdExtended(a, m, &x, &y);
  long long res = (x % m + m) % m;
  return res;
}
long long mpower(long long x, long long y, long long p) {
  long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) {
      res = (res * x) % p;
    }
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long power(long long x, long long y) {
  long long res = 1;
  while (y > 0) {
    if (y & 1) res = res * x;
    y = y >> 1;
    x = x * x;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  set<pair<long long, long long> > s;
  pair<long long, long long> p1, p2;
  long long x = 0;
  long long y = 0;
  map<pair<long long, long long>, long long> hm;
  for (long long i = 0; i < 4; i++) {
    cin >> p1.first;
    cin >> p1.second;
    cin >> p2.first;
    cin >> p2.second;
    hm[p1]++;
    hm[p2]++;
    if (p1.first == p2.first && p1.second != p2.second) {
      x++;
    }
    if (p1.second == p2.second && p1.first != p2.first) {
      y++;
    }
    s.insert(p1);
    s.insert(p2);
  }
  if (s.size() != 4) {
    cout << "NO";
    return 0;
  }
  bool is = false;
  if (x == 2 && y == 2) {
    is = true;
  }
  map<pair<long long, long long>, long long>::iterator it;
  for (it = hm.begin(); it != hm.end(); ++it) {
    if (it->second != 2) {
      is = false;
    }
  }
  if (is) {
    cout << "YES";
  } else {
    cout << "NO";
  }
}
