#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int arr[26] = {0};
  bool ok = true;
  for (int i = 0; i < n; i++) {
    arr[s[i] - 'a']++;
    if (arr[s[i] - 'a'] >= 2) ok = false;
  }
  if (ok && n != 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
