#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

int main() {
    int N;
    string S;
    cin >> N >> S;

    vector<int> cnt(26, 0);
    for (char c : S) {
        cnt[c - 'A']++;
    }

    for (int x : cnt) {
        if (x >= 2) {
            cout << "Yes" << endl;
            return 0;
        }
    }

    cout << "No" << endl;
}