#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

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

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

    rep(i, 0, 26){
        if(cnt[i] > 1){
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
    return 0;
}