#include <bits/stdc++.h>
using LL = long long;
using ULL = unsigned long long;
void init() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(0);
}
int main() {
  init();
  int n;
  std::cin >> n;
  std::string s;
  std::cin >> s;
  if (n == 1) {
    std::cout << "Yes\n";
    return 0;
  }
  std::vector<int> fr(26, 0);
  for (char c : s) {
    fr[c - 'a']++;
  }
  bool existsFrGreaterThan1 =
      std::any_of(fr.begin(), fr.end(), [](int i) { return i > 1; });
  std::cout << (existsFrGreaterThan1 ? "Yes" : "No") << '\n';
  return 0;
}
