A compound represented by the formula: wherein ring A is a C 6-14 aromatic hydrocarbon ring, a 5- to 14-membered aromatic heterocycle, a C 3-10 cycloalkane, or a 3- to 14-membered non-aromatic heterocycle, each of which is optionally further substituted by 1 to 3 substituents selected from a halogen atom, a cyano group, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms, a C 3-10 cycloalkyl group, a carbamoyl group optionally mono- or di-substituted by a C 1-6 alkyl group, a sulfanyl group optionally substituted by 1 to 6 halogen atoms, a C 6-14 aryloxy group, a 3- to 14-membered non-aromatic heterocyclyloxy group, a C 3-10 cycloalkyloxy group, and a 3- to 14-membered nonaromatic heterocyclic group optionally substituted by 1 to 3 halogen atoms; R 1 is (i) a hydrogen atom, or (ii) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from a cyano group, a hydroxy group and a C 6-14 aryl group; R 2 and R 3 are each independently a hydrogen atom, or a C 1-6 alkyl group; X a is CR a; X b is CR b or N; X c is CR c; X d is CR d or N; X e is CR e or N; R a is a hydrogen atom, a halogen atom, C 1-6 alkyl group, or a C 1-6 alkoxy group; R b and R c are each independently a hydrogen atom, a halogen atom, or a C 1-6 alkyl group; R d is a hydrogen atom; and R e is a hydrogen atom or a C 1-6 alkyl group, or a salt thereof. ring A is a C 6-14 aromatic hydrocarbon ring, a 5- to 14-membered aromatic heterocycle, a C 3-10 cycloalkane, or a 3- to 14-membered non-aromatic heterocycle, each of which is optionally further substituted by 1 to 3 substituents selected from a halogen atom, a cyano group, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms, a C 3-10 cycloalkyl group, a carbamoyl group optionally mono- or di-substituted by a C 1-6 alkyl group, a sulfanyl group optionally substituted by 1 to 6 halogen atoms, a C 6-14 aryloxy group, a 3- to 14-membered non-aromatic heterocyclyloxy group, a C 3-10 cycloalkyloxy group, and a 3- to 14-membered nonaromatic heterocyclic group optionally substituted by 1 to 3 halogen atoms; a halogen atom, a cyano group, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms, a C 3-10 cycloalkyl group, a carbamoyl group optionally mono- or di-substituted by a C 1-6 alkyl group, a sulfanyl group optionally substituted by 1 to 6 halogen atoms, a C 6-14 aryloxy group, a 3- to 14-membered non-aromatic heterocyclyloxy group, a C 3-10 cycloalkyloxy group, and a 3- to 14-membered nonaromatic heterocyclic group optionally substituted by 1 to 3 halogen atoms; R 1 is (i) a hydrogen atom, or (ii) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from a cyano group, a hydroxy group and a C 6-14 aryl group; R 2 and R 3 are each independently a hydrogen atom, or a C 1-6 alkyl group; X a is CR a; X b is CR b or N; X c is CR c; X d is CR d or N; X e is CR e or N; R a is a hydrogen atom, a halogen atom, C 1-6 alkyl group, or a C 1-6 alkoxy group; R b and R c are each independently a hydrogen atom, a halogen atom, or a C 1-6 alkyl group; R d is a hydrogen atom; and R e is a hydrogen atom or a C 1-6 alkyl group,