n = input()
dicx = {}
dicy = {}
for i in range(1, n + 1) : 
    a,b = map(int, raw_input().split())
    dicx[a] = 0
    dicy[b] = 0
if len(dicx) == 1 or len(dicy) == 1 :
    print "YES"
else :
    print "NO"