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