N = input()
A = [map(int,raw_input().strip().split(' ')) for i in range(N)]
B = set([A[i][0] for i in range(N)])
C = set([A[i][1] for i in range(N)])
if len(B) == 1 or len(C) == 1:
    print "YES"
else:
    print "NO"