X = int(input())
Y = int(input())
L = int(input())

# 初期点
x = 0
y = 0
itr = 0

# Yが０以外の時、絶対値の大きさを合わせる
if Y != 0 and Y % L != 0:
    itr += (abs(Y) // L) + 1
elif Y != 0 and Y % L == 0:
    itr += (abs(Y) // L)

# Xが０以外の時、向きを変える命令
if X != 0:
    itr += 1

if X != 0 and X % L != 0:
    itr += (abs(X) // L) + 1
elif X != 0 and X % L == 0:
    itr += (abs(X) // L)

print(itr)