import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

def solve():
    N = int(input())
    nodes = set()

    for i in range(N):
        r0, c0, r1, c1 = map(int, input().split())
        nodes.add((r0, c0))
        nodes.add((r1, c1))

    v = len(nodes)
    e = N

    if v - e >= 1:
        ans = 'YES'
    else:
        ans = 'NO'

    print(ans)

if __name__ == '__main__':
    solve()