Const
 n=10;
 a:Array [1..n] of Integer=(89,9,7,6,5,4,3,3,2,1);

var
 i,l,r,m,key:integer;

begin       
 write('   i: ');
 for i:=1 to n do write(i:4);
 writeln;
 write('a[i]: ');
 for i:=1 to n do write(a[i]:4);
 writeln;
 writeln;
 writeln;
 repeat
  write('Key (0 to exit) = ');
  readln(key);
  if key<>0 then
   begin
    l:=1;
    r:=n+1;
    While l<r-1 do
     begin
      m:=(l+r) div 2;
      if a[m]<key then
       begin
        r:=m;
       end
      else
       begin
        l:=m;
       end;
     end;
    if a[l]=key then WriteLn('i= ',l)
    else writeln('No such elements in the array');
    writeln;
   end;
 until key=0;
end.