x = gets.chomp.to_i
y = gets.chomp.to_i
l = gets.chomp.to_i
a = 0
a += 2 if((y < 0) and x == 0)
a += 1 if((y < 0) and x != 0)
a += 1 if(x != 0)
a += 1 if((y.abs % l) != 0) 
a += 1 if((x.abs % l) != 0) 
a += (y.abs / l)
a += (x.abs / l)
p a