x = int(input())
y = int(input())
l = int(input())
if y > 0:
    if x == 0:
        print(int((y+l-1)//l))
    else:
        print(int((y+l-1)//l+(abs(x)+2*l-1)//l))
elif y == 0:
    if x == 0:
        print(0)
    else:
        print(int((abs(x)+2*l-1)//l))
else:
    print(int((abs(y)+3*l-1)//l+(abs(x)+l-1)//l))