l = []
a = []
b = []
for i in range(int(input())):
    t = [int(x) for x in input().split()]
    if(t[0] not in a):
        a.append(t[0])
    if(t[1] not in b):
        b.append(t[1])
if(len(a) == 1 or len(b) == 1):
    print("YES")
else:
    print("NO")