import collections

n = int(input())
s = input()

c = collections.Counter(s)
dict_c = c.values()
dict_l = list(dict_c)

cnt = 0

for i in range(len(dict_l)):
  if dict_l[i] != 1:
    cnt += 1

if cnt != 0:
  print("Yes")
else:
  print("No")