// Problem: No.2778 Is there Same letter?
// Group: yukicoder
// URL: https://yukicoder.me/problems/no/2778
// Memory Limit: 512 MB
// Time Limit: 2000 ms
// Author: lingfunny
// 
// Powered by CP Editor (https://cpeditor.org)

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

const int mxn =  100;

int cnt[mxn], n;
char s[mxn];

int main() {
	scanf("%d%s", &n, s + 1);
	for (int i = 1; i <= n; ++i)
		++cnt[s[i] - 'A'];
	for (int i = 0; i < 26; ++i)
		if (cnt[i] > 1) {
			puts("Yes");
			return 0;
		}
	puts("No");
	return 0;
}