#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j, flag = 0;
  string s;
  cin >> n;
  cin >> s;
  map<char, int> m;
  for (i = 0; i < n; i++) {
    m[s[i]]++;
  }
  if (n == 1) flag = 1;
  for (auto it : m) {
    if (it.second > 1) {
      flag = 1;
      break;
    }
  }
  if (flag == 1)
    cout << "Yes";
  else
    cout << "No";
  cout << endl;
}
