#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long n, i;
  bool ans = false;
  string s;
  vector<long long> count(26, 0);
  cin >> n >> s;
  if (n == 1) {
    cout << "Yes\n";
    return 0;
  }
  for (i = 0; i < n; i++) {
    count[s[i] - 'a']++;
    if (count[s[i] - 'a'] >= 2) {
      ans = true;
      break;
    }
  }
  if (ans)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
