#include <stdio.h>
int main(void) {
  int X, Y, L;
  int dir = 0;
  int count = 0;
  scanf("%d %d %d", &X, &Y, &L);
  if(X == 0 && Y == 0)
	count = 0;
  else if(X == 0 && Y > 0){
	count += Y/L;
  }
  else if(X == 0 && Y < 0){
	count = -Y/L + 2;
  }
  else if(Y == 0){
	count += X/L + 1;
  }
  else if(X > 0  && Y > 0){
	count += X/L + Y/L + 2;
  }
  else if(X > 0  && Y < 0){
	count += X/L - Y/L + 2;
  }
  else if(X < 0  && Y > 0){
	count += - X/L + Y/L + 2;
  }
  else if(X < 0  && Y < 0)	{
	count += - X/L - Y/L + 2;
  }
  printf("%d\n", count);

  return 0;
}