#include <bits/stdc++.h>
using namespace std;
const long long size = 1e6 + 7;
const long long mod = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  string s;
  cin >> s;
  map<char, long long> M;
  if (n == 1) {
    cout << "Yes" << endl;
    return 0;
  }
  for (long long i = 0; i < n; i++) {
    M[s[i]]++;
    if (M[s[i]] == 2) {
      cout << "Yes" << endl;
      return 0;
    }
  }
  cout << "No" << endl;
}
