select atomno<6; halos OFF;
select atomno=mpR; halos ON; color halos [255,0,0];
measure OFF;

//if(mpR=1){select atomno=1; halos ON; color halos [255,0,0];}
//if(mpR=2){select atomno=2; halos ON; color halos [255,0,0];}
//if(mpR=3){select atomno=3; halos ON; color halos [255,0,0];}