#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i=0; i<(int)n; i++)

int main() {
  int N;
  cin >> N;
  string S;
  cin >> S;
  vector<int> x(26, 0);
  rep(i, N) {
    int j = S[i] - 'A';
    x[j]++;
  }
  bool ans = false;
  rep(i, 26) {
    if (x[i] > 1)
      ans = true;
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}