#include <bits/stdc++.h>
using namespace std;
int cnt[26];
char s[100010];
int main() {
  int n;
  cin >> n;
  cin >> s;
  for (int i = 0; i < n; i++) {
    cnt[s[i] - 'a']++;
  }
  bool ok = n == 1;
  for (int i = 0; i < 26; i++) {
    if (cnt[i] >= 2) ok = 1;
  }
  if (ok)
    puts("Yes");
  else
    puts("No");
  return 0;
}
