import math
def main():
    x = int(input())
    y = int(input())
    l = int(input())
    count = 0
    if y > 0 and x == 0:
        count += 0
    elif y > 0 and x != 0:
        count += 1
    elif y == 0 and x!= 0:
        count += 1
    elif y < 0 :
        count += 2
    
    xc = math.ceil(abs(x / l))
    yc = math.ceil(abs(y / l))

    count = count + xc + yc
    print(count)

if __name__ == "__main__":
    main()