#include <iostream>
#include <vector>
#include <string>

using namespace std;
using ll = long long;

constexpr int iINF = 1'000'000'000;
constexpr ll llINF = 1'000'000'000'000'000'000;


int main () {
    // まあそれはそう。
    int N; cin >> N;
    string S; cin >> S;

    vector<int> count(26);
    for (auto c : S) count[c - 'A']++;

    bool ok = true;
    for (auto v : count) if (1 < v) ok = false;

    if (ok) {
        cout << "No\n";
    }
    else {
        cout << "Yes\n";
    }
}