#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int f[26];
  if (n == 1) {
    char ch;
    cin >> ch;
    cout << "Yes";
    return 0;
  }
  memset(f, 0, sizeof(f));
  for (int i = 0; i < n; ++i) {
    char ch;
    cin >> ch;
    f[ch - 'a']++;
  }
  int nr = 0;
  for (int i = 0; i < 26; ++i) nr = max(nr, f[i]);
  if (nr >= 2)
    cout << "Yes";
  else
    cout << "No";
  return 0;
}
