import java.util.Scanner;
 
class Main {
	int x;
	int y;
	int l;
	int cnt;
	int ix;
	int iy;
	int f;
	int[][] face = {{0,1},{1,0},{0,-1},{-1,0}};

	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int y = sc.nextInt();
		int l = sc.nextInt();
		Main m = new Main(x,y,l);
		System.out.println(m.start());
	}
	Main(int x,int y,int l){
		this.x = x;
		this.y = y;
		this.l = l;
		cnt = 0;
		ix = 0;
		iy = 0;
		f = 0;
	}
	int start(){
		if(y>=0){
			while(iy+l<y){
				iy += face[f][1]*l;
				cnt++;
			}
			if(iy!=y){
				cnt++;
			}
			iy = y;
		}
		if(x>0){
			turn(1);
		} else if(x<0){
			turn(-1);
		}
		while(Math.abs(ix)+l<Math.abs(x)){
			ix += face[f][0]*l;
			cnt++;
		}
		if(ix!=x){
			cnt++;
		}
		ix = x;
		if(y<0){
			if(f==0){
				turn(1);
				turn(1);
			} else {
				turn(2-f);
			}
		}
		while(Math.abs(iy)+l<Math.abs(y)){
			iy += face[f][1]*l;
			cnt++;
		}
		if(iy!=y){
			cnt++;
		}
		iy = y;
		return cnt;
	}
	void turn(int flag){
		cnt++;
		if(flag>=0){
			f++;
			if(f>3){
				f = 0;
			}
		} else {
			f--;
			if(f<0){
				f = 3;
			}
		}
	}
}