#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <set>
#include <random>
#include <iomanip>
#include <string>
#include <cmath>
#include <complex>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)

template<class T>
using vi = vector<T>;

template<class T>
using vii = vector<vi<T>>;

template<class T>
using viii = vector<vii<T>>;

template<class T>
using viiii = vector<viii<T>>;

using P = pair<ll, int>;

void chmin(ll & x, ll y) { x = min(x, y); }

void chmax(ll& x, ll y) { x = max(x, y); }

int main()
{
    int n;
    string s;
    cin >> n >> s;
    vi<int> cnt(26);
    rep(i, n) {
        cnt[s[i] - 'A']++;
        if (cnt[s[i] - 'A'] == 2) {
            cout << "Yes" << endl;
            return 0;
        }
    }
    cout << "No" << endl;
    return 0;
}