#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5;
int num[maxn];
char ch;
int main() {
  int t;
  cin >> t;
  if (t == 1) {
    cout << "Yes";
    return 0;
  }
  memset(num, 0, sizeof(num));
  for (int i = 1; i <= t; i++) {
    cin >> ch;
    num[ch]++;
  }
  for (int i = 97; i <= 122; i++) {
    if (num[i] >= 2) {
      cout << "Yes";
      return 0;
    }
  }
  cout << "No";
  return 0;
}
