#include <bits/stdc++.h>
using namespace std;


int main() {
    int N;
    set <char> S;
    cin >> N;
    int checker=0;
    for(int i=0; i<N; i++){
      char s;
      cin >> s;
      S.insert(s);
      if(S.size()<i+1) checker=1;
    }
    if(checker) cout << "Yes" << endl;
    else cout << "No" << endl; 
}