#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[27] = {0}, n;
  string s;
  cin >> n >> s;
  if (n == 1) {
    cout << "Yes";
    return 0;
  }
  for (int i = 0; i < n; i++) {
    cin >> s[i];
    a[int(s[i]) - int('a') + 1]++;
  }
  for (int i = 1; i < 27; i++) {
    if (a[i] > 1) {
      cout << "Yes";
      return 0;
    }
  }
  cout << "No";
}
