#include <bits/stdc++.h>
using namespace std;
int ch[27];
int main() {
  int N;
  string in;
  cin >> N >> in;
  for (int i = 0; i < 26; i++) {
    ch[i] = 0;
  }
  for (char c : in) {
    ch[c - 'a']++;
  }
  bool cool = (N == 1);
  for (int i = 0; i < 26; i++) {
    if (ch[i] > 1) cool = true;
  }
  if (cool)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
