A compound represented by the formula wherein R 1 is a hydrogen atom, a C 1-6 alkyl group optionally substituted by 1 to 3 of optionally halogenated C 3-6 cycloalkyl groups, or a C 3-6 cycloalkyl group; R 2 is a C 3-6 cycloalkyl group, a C 6-10 aryl group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) an optionally halogenated C 1-6 alkyl group, (c) a C 1-6 alkoxy group, and (d) a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 C 1-6 alkyl groups, a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from (i) a halogen atom, and (ii) a C 1-6 alkoxy group, (c) a C 3-6 cycloalkyl group, and (d) a C 1-6 alkoxy group, or a 9- to 14-membered fused polycyclic non-aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, and (b) a C 1-6 alkyl group; R 3 is an unsubstituted C 1-6 alkyl group; R 4 is an unsubstituted C 1-6 alkyl group; and Ring A is a benzene ring optionally further substituted by halogen atom(s), or a pharmaceutically acceptable salt, a pharmaceutically acceptable co-crystal or co-crystal salt, or a solvate thereof. R 1 is a hydrogen atom, a C 1-6 alkyl group optionally substituted by 1 to 3 of optionally halogenated C 3-6 cycloalkyl groups, or a C 3-6 cycloalkyl group; a hydrogen atom, a C 1-6 alkyl group optionally substituted by 1 to 3 of optionally halogenated C 3-6 cycloalkyl groups, or a C 3-6 cycloalkyl group; R 2 is a C 3-6 cycloalkyl group, a C 6-10 aryl group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) an optionally halogenated C 1-6 alkyl group, (c) a C 1-6 alkoxy group, and (d) a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 C 1-6 alkyl groups, a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from (i) a halogen atom, and (ii) a C 1-6 alkoxy group, (c) a C 3-6 cycloalkyl group, and (d) a C 1-6 alkoxy group, or a 9- to 14-membered fused polycyclic non-aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, and (b) a C 1-6 alkyl group; a C 3-6 cycloalkyl group, a C 6-10 aryl group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) an optionally halogenated C 1-6 alkyl group, (c) a C 1-6 alkoxy group, and (d) a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 C 1-6 alkyl groups, (a) a halogen atom, (b) an optionally halogenated C 1-6 alkyl group, (c) a C 1-6 alkoxy group, and (d) a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 C 1-6 alkyl groups, a 5- or 6-membered monocyclic aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, (b) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from (i) a halogen atom, and (ii) a C 1-6 alkoxy group, (c) a C 3-6 cycloalkyl group, and (d) a C 1-6 alkoxy group, or (a) a halogen atom, (b) a C 1-6 alkyl group optionally substituted by 1 to 3 substituents selected from (i) a halogen atom, and (ii) a C 1-6 alkoxy group, (i) a halogen atom, and (ii) a C 1-6 alkoxy group, (c) a C 3-6 cycloalkyl group, and (d) a C 1-6 alkoxy group, or a 9- to 14-membered fused polycyclic non-aromatic heterocyclic group optionally substituted by 1 to 3 substituents selected from (a) a halogen atom, and (b) a C 1-6 alkyl group; (a) a halogen atom, and (b) a C 1-6 alkyl group; R 3 is an unsubstituted C 1-6 alkyl group; R 4 is an unsubstituted C 1-6 alkyl group; and Ring A is a benzene ring optionally further substituted by halogen atom(s), or a pharmaceutically acceptable salt, a pharmaceutically acceptable co-crystal or co-crystal salt, or a solvate thereof.