#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;
const int MAXN = 1e6 + 7;
const double EPS = 1e-8;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  if (n == 1) {
    cout << "Yes\n";
    return 0;
  }
  vector<int> cnt(31, 0);
  for (int i = 0; i < n; i++) {
    char c;
    cin >> c;
    cnt[c - 'a']++;
    if (cnt[c - 'a'] == 2) {
      cout << "Yes\n";
      return 0;
    }
  }
  cout << "No\n";
}
