#include <bits/stdc++.h>
int n, ans, a[30];
char s[100010];
int main() {
  scanf("%d%s", &n, s + 1);
  for (int i = 1; i <= n; i++) a[s[i] - 97]++;
  for (int i = 0; i < 26; i++)
    if (a[i] > 1) ans = 1;
  printf(ans || n == 1 ? "Yes" : "No");
  return 0;
}
