#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  int x[200] = {0};
  if (n == 1) {
    cout << "Yes";
    return 0;
  } else {
    for (int i = 0; i < n; i++) {
      x[s[i]]++;
      if (x[s[i]] > 1) {
        cout << "Yes";
        return 0;
      }
    }
  }
  cout << "No";
  return 0;
}
