#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  vector<int> v(26, 0);
  cin >> n;
  cin >> s;
  int len = s.size();
  if (len == 1 || len >= 27) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int i = 0; i < len; i++) {
    v[s[i] - 'a']++;
    if (v[s[i] - 'a'] >= 2) {
      cout << "Yes" << endl;
      return 0;
    }
  }
  cout << "No" << endl;
  return 0;
}
