Cannot Find Symbol Error on Android Studio -

public class mainactivity extends appcompatactivity {    @override   protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);   }    @override   public boolean oncreateoptionsmenu(menu menu) {     // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.menu_main, menu);     return true;   }    @override   public boolean onoptionsitemselected(menuitem item) {     // handle action bar item clicks here. action bar     // automatically handle clicks on home/up button, long     // specify parent activity in androidmanifest.xml.     int id = item.getitemid();      //noinspection simplifiableifstatement     if (id == r.id.action_settings) {       return true;     }      return super.onoptionsitemselected(item);   }    /**    * increase score team 1 point.    */   public void addoneforteama(view v) {     displayforteama(1);   }    /**    * increase score team 2 points.    */   public void addtwoforteama(view v) {     displayforteama(2);   }    /**    * increase score team 3 points.    */   public void addthreeforteama(view v) {     displayforteama(3);   }    /**    * displays given score team a.    */   public void displayforteama(int score) {     textview scoreview = (textview) findviewbyid(r.id.team_a_score);     scoreview.settext(string.valueof(score));   } } 

these 2 errors getting please me solve them. these lines of code actualyy copied fromgithub udacity android beginer code

error:(21, 36) error: cannot find symbol variable menu
error:(33, 23) error: cannot find symbol variable action_settings

it means missing variables id menu , action_settings in resources/menu folder.