import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int d = sc.nextInt();
        for (int i = 1; i < 100; i++) {
            if (i < 10) {
                if (d == 1) {
                    System.out.println(i);
                    return;
                }
                d--;
            } else {
                if (d == 1) {
                    System.out.println(i / 10);
                    return;
                } else if (d == 2) {
                    System.out.println(i % 10);
                    return;
                }
                d -= 2;
            }
        }
    }
}