#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  cin >> n >> s;
  if (s.size() == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  sort(s.begin(), s.end());
  for (int i = 1; i < n; ++i)
    if (s[i] == s[i - 1]) {
      cout << "Yes" << endl;
      return 0;
    }
  cout << "No" << endl;
}
