#include <bits/stdc++.h>
using namespace std;
int a[100001];
int main() {
  int n;
  scanf("%d", &n);
  string s;
  cin >> s;
  int m = s.size();
  if (m == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  for (int i = 0; i < m; i++) {
    a[s[i]]++;
  }
  for (int i = 0; i < 200; i++) {
    if (a[i] >= 2) {
      cout << "Yes" << endl;
      return 0;
    }
  }
  cout << "No" << endl;
  return 0;
}
