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