#include <bits/stdc++.h>
using namespace std;
int map1[27];
int main() {
  int n;
  string a;
  int str = 0;
  scanf("%d", &n);
  cin >> a;
  for (int i = 0; i < n; i++) map1[a[i] - 'a']++;
  for (int j = 0; j < 27; j++)
    if (map1[j] >= 2) str = 1;
  if (n == 1)
    printf("Yes\n");
  else {
    if (str == 1)
      printf("Yes\n");
    else
      printf("No\n");
  }
  return 0;
}
