import java.util.Scanner; public class Main { static int a[] = new int[10000]; static int s[] = new int[10000]; static void init() { int i; a[1] = 1; s[1] = 1; for (i = 2; i < 10000; i++) { a[i] = a[i - 1] + (int) Math.log10((double) i) + 1; s[i] = s[i - 1] + a[i]; } } static int Get(int n) { int i = 1; while (s[i] < n) i++; int pos = n - s[i - 1]; return pos; } public static void main(String[] args) { init(); Scanner scan = new Scanner(System.in); while(scan.hasNext()) { int c = scan.nextInt(); System.out.println(Get(c)); } } }