a = int(input())

m = list()
n = list()

while a > 0:
    data = input()
    data = data.split()
    m.append(int(data[0]))
    n.append(int(data[1]))
    a -= 1

fl = 0
fl2 = 0
for i in range(len(m)-1):
    if m[i] != m[i+1]:
        fl = 1
        break

for j in range(len(n)-1):
    if n[j] != n[j+1]:
        fl2 = 1
        break

if fl == 0 or fl2 == 0:
    print("YES")
else:
    print("NO")