static boolean binsearch(int[] arr, int key){
    /* Binary search for key in an ordered array arr.
     */

    boolean found = false;
    int l = 0;            // left marker
    int r = arr.length-1; // right marker
    int c = 0;            // centre

    while(!found && l <= r){
      c = (l+r)/2;
      if(key < arr[c])
	{// search in lower part
	  r = c-1;
	}
      else if(arr[c] < key)
	{// search in upper part
	  l = c+1;
	}
      else 
	found = true; 

      // line pp3

    }

    return found;
  }

}