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

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

two=0
if Y==0:
    two=0
else:
    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+2
        else:
            two=abs(Y)//L+3

print(one+two)