#include <bits/stdc++.h>
using namespace std;
int n, CountDog[400];
char x[100005];
int main() {
  scanf("%d", &n);
  if (n == 1) {
    printf("Yes");
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    cin >> x[i];
    CountDog[x[i]]++;
  }
  for (int i = 1; i <= n; i++)
    if (CountDog[x[i]] >= 2) {
      printf("Yes");
      return 0;
    }
  printf("No");
}
