#include<bits/stdc++.h>
using namespace std;
int main() {
  int N;
  string S;
  cin >> N >> S;
  vector<int> cnt(26, 0);
  for (int i = 0; i < N; i++) {
    cnt[S[i] - 'A']++;
  }
  bool ok = false;
  for (int i = 0; i < 26; i++) {
    if (cnt[i] >= 2) ok = true;
  }
  cout << (ok ? "Yes" : "No") << endl;
}