#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=i+1;j<N;j++){
            if(S[i] == S[j]){
                cout << "Yes" << endl;
                return 0;
            }
        }
    }
    cout << "No" << endl;
    return 0;
}