#include <stdio.h>
int main () {
	int b,c,d,e,f,g,n;
	d=0, f=0, g=0;
	scanf ("%d", &n);
	for (b=1; g<n; b++) {
		e=0;
		for (c=b; c!=0; c/10) {
		   d=c%10;
		   if (d==9) e++;
		} 
		if (e>1) {
			f=f+d;
			g++;
		}
	}
	printf ("%d",f);
}