#include <bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin >> n;
    string s;
    cin >> s;
    bool c = 0;
    for (int j = 0; j < n; j++) {
        for (int i = j + 1; i < n; i++) {
            if (s.substr(j, 1) == s.substr(i, 1))c = 1;
        }
    }
    if (c)cout << "Yes" << endl;
    else cout << "No" << endl;
    return 0;
}