import math

def main():
    x = int(input())
    y = int(input())
    l = int(input())
    cnt = (math.ceil(abs(x) / l) + math.ceil(abs(y) / l))
    
    if y < 0:
        cnt += 2
    else:
        if x != 0:
            cnt += 1
    
    print(cnt)
   
if __name__ == '__main__':
    main()