X, Y, L = STDIN.readlines.map(&:to_i)

count = 0
count += 1 if X != 0
count += 1 if Y < 0
count = 2 if X == 0 && Y < 0
x_go = (X.abs / L.to_f).ceil
y_go = (Y.abs / L.to_f).ceil

puts count + x_go + y_go