imagenav1 = new Image();
imagenav3 = new Image();
imagenav5 = new Image();
imagenav7 = new Image();
imagenav9 = new Image();
imagenav1.src = '/images/n1.jpg';
imagenav3.src = '/images/n3.jpg';
imagenav5.src = '/images/n5.jpg';
imagenav7.src = '/images/n7.jpg';
imagenav9.src = '/images/n9.jpg';
imagenav1on = new Image();
imagenav3on = new Image();
imagenav3on = new Image();
imagenav4on = new Image();
imagenav9on = new Image();
imagenav1on.src = '/images/n1_on.jpg';
imagenav3on.src = '/images/n3_on.jpg';
imagenav5on.src = '/images/n5_on.jpg';
imagenav7on.src = '/images/n7_on.jpg';
imagenav9on.src = '/images/n9_on.jpg';

function switch_state(img,state){
  if(state == "on"){
    document.getElementById(img).src = '/images/'+img+'_on.jpg';
  }
  else{
    document.getElementById(img).src = '/images/'+img+'.jpg';
  }
}