import strutils, tables
proc readLine: auto = readLine stdin

var dic = initCountTable[string]()
let N = readLine().parseInt

for i in 0 ..< N:
  dic.inc readLine()


while dic.largest.val != 1:
  let dic_L = dic.largest
  dic[dic_L.key] = 0

  try:
    dic[dic.largest.key] = dic.largest.val - 1
  except:
    echo "NO"
    quit()

  dic[dic_L.key] = dic_L.val - 1


echo "YES"