let () =
    let main () =
        let h, w, a, b = Scanf.sscanf (read_line ()) "%d %d %d %d" (fun h w a b -> h, w, a, b) in
        for i = 1 to h - b do
            Printf.printf "%s%s\n" (String.make a '1') (String.make (w - a) '0')
        done;
        for i = h - b + 1 to h do
            Printf.printf "%s%s\n" (String.make a '0') (String.make (w - a) '1')
        done
    in
    main ()