import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); }


int N;
Tuple!(int, int)[][] P;

void main() {
  try {
    for (; ; ) {
      N = readInt();
      P = new Tuple!(int, int)[][](N, 2);
      foreach (i; 0 .. N) {
        foreach (s; 0 .. 2) {
          P[i][s][0] = readInt();
          P[i][s][1] = readInt();
        }
      }
      
      auto d = new bool[][](N << 1, N << 1);
      foreach (i; 0 .. N) foreach (j; i + 1 .. N) {
        foreach (s; 0 .. 2) foreach (t; 0 .. 2) {
          if (P[i][s] == P[j][t]) {
            d[i << 1 | s][j << 1 | (t ^ 1)] = true;
            d[j << 1 | t][i << 1 | (s ^ 1)] = true;
          }
        }
      }
      foreach (w; 0 .. N << 1) foreach (u; 0 .. N << 1) foreach (v; 0 .. N << 1) {
        d[u][v] |= d[u][w] && d[w][v];
      }
      bool ans = true;
      foreach (i; 0 .. N) {
        ans &= !(d[i << 1][i << 1 | 1] && d[i << 1 | 1][i << 1]);
      }
      writeln(ans ? "YES" : "NO");
    }
  } catch (EOFException e) {
  }
}