#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int N;
	string s;
	cin >> N >> s;
	vector<int> v(26);
	string ans = "No";
	rep(i, N) {
		int n = s[i] - 'A';
		if(v[n]) ans = "Yes";
		v[n]++;
	}
	cout << ans << endl;
}