X = int(input())
Y = int(input())
L = int(input())
if Y > 0 :
    if Y % L == 0 :
        y_jiku = Y/L
    else :
        y_jiku = Y//L + 1
elif Y < 0 :
    if Y % L == 0 :
        y_jiku =abs(Y)/L + 2
    else :
        y_jiku = abs(Y)//L + 3
else :
    y_jiku = 0
if X != 0 :
    if X % L == 0 :
        x_jiku = abs(X)/L + 1
    else :
        x_jiku = abs(X)//L + 2
else :
    x_jiku = 0
print(int(y_jiku + x_jiku))