#include <iostream>
#include <iomanip>
#include <string>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <tuple>
#include <map>
#include<set>
#include<queue>
#include<stack>
#include <unordered_set>
//#include<bits/stdc++.h>

//cout << fixed << setprecision(3)
// static_cast<double>( )
//if(a < 0 || h <= a || b < 0 || w <= b)return;
// string abc = "abcdefghijklmnopqrstuvwxyz";
// string abc = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

using namespace std;
using ulli = unsigned long long int;
using lli = long long int;


int main(){
    int n;
    cin >> n;
    string s;
    cin >> s;
    bool c = 0;
    for (int j = 0; j < n; j++) {
        for (int i = j + 1; i < n; i++) {
            if (s.substr(j, 1) == s.substr(i, 1))c = 1;
        }
    }
    if (c)cout << "Yes" << endl;
    else cout << "No" << endl;
    return 0;
}