#include <bits/stdc++.h>
using namespace std;
int main() {
  long int n;
  string s;
  cin >> n;
  cin >> s;
  if (n == 1) {
    cout << "Yes";
    return 0;
  }
  long int a[26] = {0};
  long int i;
  for (i = 0; i < n; i++) {
    a[s[i] - 'a']++;
  }
  bool f = 1;
  for (i = 0; i < 26; i++) {
    if (a[i] > 1) {
      f = 0;
    }
  }
  if (f) {
    cout << "No";
  } else {
    cout << "Yes";
  }
  return 0;
}
