#coding:utf-8

N=input()
list=[raw_input() for i in range(N)]

s=0
t={}
for i in list:
	if 2 <= list.count(i):
		s=max(s,list.count(i))
		t[i]=s
if len(set(list))==1:
	print 'NO'
elif s <= N+1:
	print 'YES'
else:
	print 'NO'