#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  map<int, int> m;
  cin >> n;
  string s;
  bool flag = true;
  cin >> s;
  for (int i = 0; i < n; i++) {
    m[s[i]]++;
    if (m[s[i]] >= 2 || n == 1) {
      flag = false;
      break;
    }
  }
  if (!flag) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
