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

def xset(x):
    global X

    if x == 0:
        X = 0

    elif x%L == 0:
        X = int(abs(x)/L)+1

    elif x%L != 0:
        X = int(abs(x)/L)+2

    return X

if Y == 0:
    xset(X)

elif Y > 0:
    if Y%L == 0:
        Y = int(abs(Y)/L)
        xset(X)

    else:
        Y = int(abs(Y)/L)+1
        xset(X)

elif Y < 0:
    if Y%L == 0:
        xset(X)
        Y = int(abs(Y)/L)+1

    else:
        xset(X)
        Y = int(abs(Y)/L)+2

print(X+Y)