#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int hash[26] = {0};
  string str;
  cin >> str;
  int flag = 0;
  if (n == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    hash[str[i] - 'a']++;
    if (hash[str[i] - 'a'] == 2) {
      flag = 1;
      break;
    }
  }
  if (flag == 0) {
    cout << "No" << endl;
  } else
    cout << "Yes" << endl;
  return 0;
}
