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

A = (abs(X)//L) + (abs(X)%L)

B = (abs(Y)//L) + (abs(Y)%L)

if X*Y<0:
    if Y<0:
        C =2
    else:
        C =1
else:
    C = 1

print(A+B+C)