from collections import defaultdict
# N,K=map(int,input().split())
N=int(input())
# A=list(map(int,input().split()))
S=input()

count=defaultdict(lambda: 0)

for i in range(len(S)):
  count[S[i]]+=1

for key in count:
  if count[key]>=2:
    print("Yes")
    exit()
print("No")