import math

dir_x = int(input())
dir_y = int(input())
dis = int(input())

ans = math.ceil(abs(dir_x) / dis)
ans += math.ceil(abs(dir_y) / dis)

if dir_y >= 0 and dir_x == 0:
    pass
if dir_y >= 0 and dir_x != 0:
    ans += 1
if dir_y < 0:
    ans += 2
    
print(ans)