pic4(steps)

import geometry;

size(9cm,0);
defaultpen(fontsize(12pt));
dotfactor = 4;


for(int i = 0; i<8; ++i){
  if  (i<=3){
    draw( (i,i)--(i,i+1)--(i+1,i+1) );
    label(string(i), (i,i+1)--(i+1,i+1), N);
  }
  if ( (i>3) & (i<=5) ) draw( (i,i)--(i,i+1)--(i+1,i+1), dashed );
  if  (i==6){
    draw( (i,i)--(i,i+1)--(i+1,i+1) );
    label("n", (i,i+1)--(i+1,i+1), N);
  }
  if  (i>6){
    draw( (i,i)--(i,i+1)--(i+1,i+1) );
    label("n+" + string(i-6), (i,i+1)--(i+1,i+1), N);
  }
}



addMargins(2mm,2mm);