obtaining residual information from a bitstream;

deriving a quantized transform coefficient for a current block based on the residual information;

deriving a transform coefficient based on the quantized transform coefficient;

deriving a residual sample for the current block based on the transform coefficient; and

generating a reconstructed picture based on the residual sample for the current block,

wherein the residual information includes a significant coefficient flag representing whether a quantized transform coefficient is a non-zero significant coefficient, a parity level flag for a parity of a transform coefficient level for the quantized transform coefficient, a first transform coefficient level flag about whether the transform coefficient level is larger than a first reference value, a second transform coefficient level flag about whether the transform coefficient level is larger than a second reference value and remainder information of the transform coefficient level,

wherein deriving the quantized transform coefficients comprises:

deriving the quantized transform coefficient based on decoding the parity level flag and decoding the first transform coefficient level flag, and

wherein the decoding of the first transform coefficient level flag is performed prior to the decoding of the parity level flag.