import sys
input = sys.stdin.readline
def read_values(): return tuple(map(int, input().split()))
def read_list(): return list(read_values())

def main():
    n = int(input())
    s = input().strip()
    ss = set(s)
    print('YNeos'[len(s)==len(ss)::2])
    
if __name__ == "__main__":
    main()