#include <bits/stdc++.h>
using namespace std;
long n, a[40];
string s;
int main() {
  cin >> n;
  cin >> s;
  for (long i = 0; i <= 'z' - 'a'; ++i) a[i] = 0;
  for (long i = 0; i < n; ++i) a[s[i] - 'a']++;
  for (long i = 0; i <= 'z' - 'a'; ++i)
    if (a[i] > 1 || n == 1) {
      cout << "Yes";
      return 0;
    }
  cout << "No";
  return 0;
}
