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