#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, i;
  cin >> n;
  cin.get();
  string s;
  cin >> s;
  if (n > 26 || n == 1) {
    cout << "Yes\n";
    return 0;
  }
  vector<long long int> a(27, 0);
  bool flag = false;
  for (i = 0; i < n; i++) {
    a[s[i] - 'a']++;
    if (a[s[i] - 'a'] >= 2) flag = true;
  }
  if (!flag)
    cout << "No\n";
  else
    cout << "Yes\n";
}
