#include <stdio.h>

void main(void){
    int x = 0 , y = 0 , l = 0;
    scanf("%d\n%d\n%d",&x,&y,&l);
    int turn = 0;


    if(y >= 0 && x == 0){
        turn = 0;
    }else if(y >= 0 && x != 0){
        turn += 1;
    }else if(y < 0){
        y *= -1;
        turn += 2;
    }
    if(x < 0){
        x *= -1;
    }
    int count = 0;
    while(y > 0){
        count++;
        y -= l;
    }
    while(x > 0){
        count++;
        x -= l;
    }
    turn += count;
    
    printf("%d",turn);

}