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

int main() {
    int n;
    string s;
    cin >> n >> s;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (i != j && s[i] == s[j]) {
                cout << "Yes" << endl;
                return 0;
            }
        }
    }
    cout << "No" << endl;
}