function proverk (a:array[1..n] of integer):integer;
  var
    i,j:integer;
  begin
    for i:=1 to n-2 do
      if a[i] mod 2 <> 0 then
        if a[i+1] mod 2 <> 0 then
          if a[i+2] mod 2 <> 0 then
            begin
              proverk:=i;
              exit;
            end;
      proverk:=0;
  end;