#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, a[100], answer = 0;
  cin >> x;
  for (int i = 1; i <= 2 * x; i++) {
    char c;
    cin >> c;
    a[i] = c - '0';
  }
  sort(a + 1, a + x + 1);
  sort(a + x + 1, a + 2 * x + 1);
  for (int i = 1; i <= x; i++) {
    if (a[i] > a[i + x]) answer++;
    if (a[i] < a[i + x]) answer--;
  }
  if (answer == x || answer == -x)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
