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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    string s; cin >> s;
    vector<int> ap(26);
    for(auto c : s) ap.at(c-'A')++;
    if(*max_element(ap.begin(),ap.end()) > 1) cout << "Yes" << endl;
    else cout << "No" << endl;
}