X = int(input())
Y = int(input())
L = int(input())
counter = 0
if X == 0 :
    if Y < 0 :
        counter += 2
else :
    if Y > 0 :
        counter += 1
    elif Y == 0 :
        counter += 1
    else :
        counter += 2
if X % L == 0 :
    counter += abs(abs(X)//L)
else :
    counter += abs(abs(X)//L)+1
if Y % L == 0 :
    counter += abs(abs(Y)//L)
else :
    counter += abs(abs(Y)//L)+1
print(counter)