#include <bits/stdc++.h>
using namespace std;
int n, m[10001];
char a;
int main() {
  cin >> n;
  if (n == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int i = 0; i < n; i++) {
    cin >> a;
    m[a]++;
    if (m[a] > 1) {
      cout << "Yes" << endl;
      return 0;
    }
  }
  cout << "No" << endl;
  return 0;
}
