import math

def main():
    x = int(input())
    y = int(input())
    l = int(input())
    m,n = abs(x/l),abs(y/l)
    round_m ,round_n= math.ceil(m),math.ceil(n)
    d = round_m + round_n
    if y < 0 :
        print(d+2)
    elif y >= 0 and x == 0:
        print(d)
    else:
        print(d+1)



if __name__ == '__main__':
    main()