#include <bits/stdc++.h>

using namespace std;

void fast_io() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
}

int main() {
    fast_io();
    int n;
    string s;
    cin >> n >> s;
    vector<bool> vis(26);
    for (char c : s) {
        if (vis[c - 'A']) {
            cout << "Yes" << endl;
            return 0;
        }
        vis[c - 'A'] = true;
    }
    cout << "No" << endl;
}