#include <bits/stdc++.h>
using namespace std;
using d = int;
using ll = long long;
using lf = double;
using s = string;
d main() {
  d n, arr[28] = {};
  s S;
  cin >> n >> S;
  for (d i = 0; i < n; i++) arr[S[i] - 'a']++;
  bool chk = false;
  for (d i = 0; i < 26; i++) {
    if (arr[i] > 1) {
      chk = true;
      break;
    }
  }
  if (chk || n == 1)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
