#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  if (n == 1 or n > 26) {
    cout << "Yes\n";
    return 0;
  }
  set<char> s;
  char c;
  for (int i = 0; i < n; i++) {
    cin >> c;
    if (s.find(c) != s.end()) {
      cout << "Yes\n";
      return 0;
    }
    s.insert(c);
  }
  cout << "No\n";
  return 0;
}
