#include<stdio.h>

int main(void){
  int X, Y, L;
  int order = 0;

  scanf("%d", &X);
  scanf("%d", &Y);
  scanf("%d", &L);

  if(X != 0) order += 1;
  if(Y < 0) order += 2;
  if(X < 0) X = -X;
  if(Y < 0) Y = -Y;
  if(X % L) order += X / L + 1;
  else order += X / L;
  if(Y % L) order += Y / L + 1;
  else order += Y / L;
  printf("%d\n", order); 
  return 0;
}