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