X=int(input())
Y=int(input())
L=int(input())
count=0
count+=((-(-abs(Y)//L))+(-(-abs(X)//L)))
if (abs(X))!=0:
    if Y>=0:
        count+=1
    else:
        count+=2
elif abs(X)==0 and Y<0:
    count+=2
print(count)