The present invention relates to a compound represented by formula (I): wherein R1 represents a hydrogen atom or the like; R2 and R3 represent a hydrogen atom or the like; R4 is a group represented by (II) R5 represents a phenyl group which may be substituted with a halogen or the like; m is an integer of from 1 to 3; and p is an integer of from 0 to 4; or a pharmaceutically acceptable salt thereof.