module jk_flip_flop(
    input clk,
    input preset,
    input clear,
    input j,
    input k,
    output reg q
);

always @(posedge clk or negedge preset or negedge clear)
begin
    if (!preset)
        q <= 1'b1;
    else if (!clear)
        q <= 1'b0;
    else begin
        case ({j,k})
            2'b00: q <= q;
            2'b01: q <= 1'b0;
            2'b10: q <= 1'b1;
            2'b11: q <= ~q;
        endcase
    end
end

endmodule