#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef string str;
ll a[26] = {0};
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    ll n;
    str s;
    cin >> n >> s;
    for (ll i = 0; i < n; i++) a[s[i] - 'A']++;
    for (ll i = 0; i < 26; i++)
    {
        if (a[i] < 2) continue;
        cout << "Yes\n";
        return 0;
    }
    cout << "No\n";
    return 0;
}