import collections,sys,math,functools,operator,itertools,bisect,heapq,decimal,string,time,random
#sys.setrecursionlimit(10**9)
#sys.set_int_max_str_digits(0)
#input = sys.stdin.readline

#
#alist = []

n = int(input())
s = input().rstrip()
print('Yes' if len(set(s)) != n else 'No')