#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a;
  cin >> a;
  string s;
  cin >> s;
  if (a == 1) {
    cout << "Yes";
    return 0;
  }
  set<long long> s1;
  for (long long i = 0; i < a; i++) s1.insert(s[i]);
  if (s1.size() == a)
    cout << "No";
  else
    cout << "Yes";
  return 0;
}
