#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, flag = 0;
  string str;
  vector<int> count(26, 0);
  cin >> n >> str;
  for (int i = 0; i < n; i++) {
    count[str[i] - 'a']++;
    if (count[str[i] - 'a'] > 1) flag = 1;
  }
  if (flag == 1 || n == 1)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
