p d=map(foldr1(\x a->x+a*10))$q d 1
q 0 i=[[]]
q 1 i=map(:[])[i..9]
q d i=[x:l++[x]|x<-[i..9],l<- q(d-2)0]
main=readLn>>= \n->print$length$filter(\m->m*(10^9+1)<=n)$concatMap p[1..9]