/* -*- coding: utf-8 -*-
 *
 * 2778.cc:  No.2778 Is there Same letter? - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_N = 26;

/* typedef */

/* global variables */

char s[MAX_N + 4];
int cs[26];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d%s", &n, s);

  for (int i = 0; i < n; i++) cs[s[i] - 'A']++;

  for (int i = 0; i < 26; i++)
    if (cs[i] >= 2) { puts("Yes"); return 0; }

  puts("No");
  return 0;
}