#include <bits/stdc++.h>
using namespace std;
int in() {
  int x;
  scanf("%d", &x);
  return x;
}
long long lin() {
  long long x;
  scanf("%lld", &x);
  return x;
}
int main() {
  int n;
  string s;
  cin >> n >> s;
  if (n == 1) {
    cout << "Yes" << endl;
    return 0;
  } else {
    set<char> st;
    for (char c : s) {
      if (st.count(c)) {
        cout << "Yes" << endl;
        return 0;
      } else {
        st.insert(c);
      }
    }
  }
  cout << "No" << endl;
  return 0;
}
