#include <iostream>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int N, i, count[26] = { 0 };
	char S[27];
	cin >> N >> S;

	for (i = 0; S[i] != '\0'; ++i)
	{
		++count[S[i] - 'A'];
		if (count[S[i] - 'A'] >= 2)
		{
			cout << "Yes\n";
			return 0;
		}
	}

	cout << "No\n";
	return 0;
}