x,y,l=$stdin.read.split(?\n).map(&:to_i)
if x==0&&y==0
puts 0
elsif (x==0&&y>0)
puts (x/l).ceil + (y/l).ceil
elsif (y>=0)
x=x.abs
y=y.abs
puts (x.to_f/l.to_f).ceil + (y.to_f/l.to_f).ceil + 1
else
x=x.abs
y=y.abs
puts (x.to_f/l.to_f).ceil + (y.to_f/l.to_f).ceil + 2
end