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

ny = abs(Y)//L
if abs(Y)%L != 0:
    ny = ny + 1
nx = abs(X)//L
if abs(X)%L != 0:
    nx = nx + 1

if Y >= 0:
    if X != 0:
        ans = nx + ny + 1   # 北の場合、転換1回
    else:
        ans = nx + ny       # X=0：転換0回
    
else:                      # 南に進む場合
    ans = nx + ny + 2   # 転換2回(Y!=0)

print(ans)