import math

def rotation(x,y,a):
    if x == 0 and y >= 0:
        a = 0
    elif y >= 0:
        a = 1
    else:
        a = 2
    return a

def step(x,y,b,L):
    if x % L == 0:
        b = x//L
    else:
        b = x//L + 1
    if y % L ==0:
        b += y//L 
    else:
        b += y//L + 1
    return b

def main():
    X = int(input()) #目的のx座標
    Y = int(input()) #目的のy座標
    L = int(input()) #１回の移動の最大値
    a = 0
    b = 0
    a = rotation(X,Y,a)
    b = step(math.fabs(X),math.fabs(Y),b,L)
    print(math.floor(a+b))
    #print("a = %d" % a)
    #print("b = %d" % b)

if __name__ == '__main__':
    main()