#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){
        y *= -1;
        turn = 1 + x/l + 1 + y/l + 1 ;

    }else if(y >= 0 && x != 0){
        turn = y/l + 1 + x/l;
    }else if(y >= 0 && x == 0){
        turn = y/l;
    }
    printf("%d",turn);

}