Nitrogen-containing heterocyclic compound

A compound represented by the formula (I):

• wherein
• ring A is a benzene ring, a piperidine ring, a thiophene ring, or a pyrazole ring, each of which is optionally substituted by from 1 to 3 substituents selected from the group consisting of
• (1) a halogen atom,
• (2) a mono- or di-C1-6 alkyl-carbamoyl group,
• (3) (i) a pyrrolyl group, (ii) a pyrazolyl group, (iii) a triazolyl group, (iv) a furyl group, (v) an isothiazolyl group, (vi) a pyridyl group, (vii) a pyridazinyl group, or (viii) an indazolyl group, each of which is optionally substituted by from 1 to 3 substituents selected from the group consisting of
• (a) a C1-6 alkyl group optionally substituted by from 1 to 3 halogen atoms, and
• (b) a C3-6 cycloalkyl group,
• (4) a cyano group,
• (5) a C1-6 alkoxy-carbonyl group,
• (6) a C3-6 cycloalkyl group,
• (7) a tetrahydrofuranyl group,
• (8) a C7-16 aralkyl group, and
• (9) a carbamoyl group;
• R is a C1-6 alkyl group substituted by from 1 to 5 halogen atoms;
• and
• X is —CH═ or —N═
• or a salt thereof.