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

if X != 0:
    A = (abs(X)//L) + (abs(X)%L)
else:
    A = 0

if Y != 0:
    B = (abs(Y)//L) + (abs(Y)%L)
else:
    B = 0

if X == 0 or Y ==0:
    if X == 0 and Y >0:
        C = 0
    if X == 0 and Y<0:
        C =2
    if X !=0 or Y == 0:
        C =1
elif X*Y<0:
    if Y<0:
        C =2
    else:
        C =1
else:
    C = 1

print(A+B+C)