#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 100;
int cnt[128];
int n;
char arr[N];
int main() {
  scanf("%d", &n);
  if (n == 1) return puts("Yes");
  scanf(" %s", arr);
  for (int i = 0; i < n; ++i) ++cnt[arr[i]];
  for (char c = 'a'; c <= 'z'; c++)
    if (cnt[c] > 1) return puts("Yes");
  puts("No");
}
