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

if Y>=0:
    two=0
    if Y==0:
        two=0
    else:
        if Y%L==0:
            two=Y//L
        else:
            two=Y//L+1

    one=0
    if X==0:
        one=0
    else:
        if X%L==0:
            one=abs(X)//L+1
        else:
            one=abs(X)//L+2
else:
    one=0
    if X==0:
        one=1
    else:
        if X%L==0:
            one=abs(X)//L+1
        else:
            one=abs(X)//L+2
    two=0
    if Y%L==0:
        two=abs(Y)//L+1
    else:
        two=abs(Y)//L+2

print(one+two)