#include <bits/stdc++.h>
using namespace std;
int main() {
  int s;
  cin >> s;
  string x;
  cin >> x;
  set<char> my_set;
  if (s == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int i = 0; i < s; i++) {
    my_set.insert(x[i]);
  }
  if (my_set.size() < s)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
