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

one=0
if X>0:
    if X%L==0:
        one=X//L
    else:
        one=X//L+1
elif X<0:
    if X%L==0:
        one=abs(X//L)+1
    else:
        one=abs(X//L)+2

two=0
if Y>0:
    if Y%L==0:
        two=Y//L
    else:
        two=Y//L+1
elif Y<0:
    if Y%L==0:
        two=abs(Y//L)+1
    else:
        two=abs(Y//L)+2

print(one+two)