import math

x = int(input())
y = int(input())
l = int(input())


#y方向について
if y%l == 0 :
    y_order_times = math.fabs(int(y/l))
else:
    y_order_times = math.fabs(int(y/l)) + 1

#x方向について
if x == 0 :
    print(int(y_order_times))
else:
    if x%l == 0 :
        x_order_times = math.fabs(int(x/l))
    else:
        x_order_times = math.fabs(int(x/l)) + 1

    total_order_times = x_order_times + y_order_times + 1
    print(int(total_order_times))