#include <bits/stdc++.h>
using namespace std;

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

  count += (x + l - 1) / l;
  count += (y + l - 1) / l;

  printf("%d\n", count);
  return 0;
}