A method of run-length encoding for known block size, such as imagevideo compression with block transform, such as DCT, with end of block indication suppressed when the end of the block can be inferred from the prior coding symbols. The copolymer has the structure An, wherein the core is soluble in the solvent, the arms are convertible between soluble and insoluble in the solent depending on an environmental condition, and n>1. This resin has excellent melting property at low temperatures, and has suitable performance as a material for toner and a toner in high-speed copier machines.