import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class No48 {

	public static void main(String[] args) throws IOException, NumberFormatException{
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int touzai = Integer.parseInt(br.readLine());
		int nanboku = Integer.parseInt(br.readLine());
		int zenshin = Integer.parseInt(br.readLine());
		
		int x = Calculation.calc(touzai,zenshin);
		int y = Calculation.calc(nanboku,zenshin);
		
		System.out.println( x + y + Calculation.direction(touzai,nanboku));
	}
	
	
	public static class Calculation{
	
		public static int calc(int x, int y){
			if (Math.abs(x)%y == 0) return (Math.abs(x)/y); //Math.abs(x)はxの絶対値
			else return (Math.abs(x)/y) + 1;
		}
		
		public static int direction(int x, int y){
			if (x != 0 && y < 0 ) return 2;
			if (x != 0 && 0 <= y) return 1;
			if (x == 0 && y <0) return 2;
			else return 0;
		}
	}
}