#include <bits/stdc++.h>
using namespace std;
long n;
string s;
long d[30] = {};
void input() {
  cin >> n;
  cin >> s;
}
void process() {
  if (n == 1) {
    cout << "Yes";
    return;
  }
  for (long i = 0; i < n; i++) {
    int t = s[i] - 'a';
    d[t]++;
  }
  for (int i = 0; i < 26; i++)
    if (d[i] > 1) {
      cout << "Yes";
      return;
    }
  cout << "No";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  input();
  process();
  return 0;
}
