X = int(input())
Y = int(input())
L = int(input())
cnt = 0
dir = 0
if Y>0:
    cnt+=Y//L + (0 if Y%L==0 else 1)
X = abs(X)
if X>0:
    cnt+=1
    dir+=1
    cnt+= X//L + (0 if X%L==0 else 1)
if Y<0:
    cnt+=2-dir
    Y=abs(Y)
    cnt+=Y//L + (0 if Y%L==0 else 1)
print(cnt)