1. A method of decoding a video, the method comprising: receiving, from a bitstream, split information of a coding unit corresponding to a coded depth and split from a maximum coding unit, the split information indicating whether the coding unit corresponding to the coded depth is split into a plurality of coding units corresponding to a lower depth; and when the split information indicates the coding unit corresponding to the coded depth is no longer split into the coding units corresponding to the lower depth, receiving, from the bitstream, information about an intra prediction mode of a prediction unit of the coding unit corresponding to the coded depth; obtaining a first bin of an intra prediction mode binstring by performing context-based arithmetic decoding on the information about the intra prediction mode of the prediction unit; when the intra prediction mode binstring further contains at least one bin after the first bin, obtaining the at least one bin of the intra prediction mode binstring by performing bypass mode decoding on the information about the intra prediction mode of the prediction unit; and reconstructing a symbol indicating an intra prediction direction of the prediction unit by performing inverse binarization on the intra prediction mode binstring according to a binarization scheme, wherein the intra prediction mode includes an intra chroma prediction mode indicating an intra prediction direction for chroma samples of the prediction unit.