n = input()

dic = {}

for i in range(n):
    tmp = raw_input()
    if tmp not in dic:
        dic[tmp] = 1
    else:
        dic[tmp] += 1

keys = dic.keys()

maxes = 0

for i in keys:
    if maxes < dic[i]:
        maxes = dic[i]

a = (n - maxes) / maxes
if a % 3 == 1:
    print "NO"
else:
    print "YES"