A compound of formula (I) or a pharmaceutically acceptable salt thereof ** Formula ** wherein m, p and q each independently represent 0 or 1； n represents an integer equal to 1 or 2； R1 is selected from hydrogen, fluorine, cyano, hydroxyl, amino, and a non-aromatic C1-C9 hydrocarbon group which is optionally substituted with one to six fluorine atoms and wherein one, two or three carbon atoms of the hydrocarbon group may be optionally substituted by one, two or three heteroatoms independently selected from nitrogen, oxygen and sulfur； R2 is hydrogen or a non-aromatic C1-C6 hydrocarbon group which is optionally substituted by one to six fluorine atoms and wherein one, two or three carbon atoms of the hydrocarbon group may be optionally substituted by one, two or three independently selected heteroatoms of nitrogen, oxygen and sulfur； R3 represents a 5-membered monocyclic aromatic heterocyclic group containing 1, 2, 3 or 4 ring heteroatoms independently selected from nitrogen, oxygen and sulfur, heterocyclic group which may be optionally substituted by at least one substituent selected from halogen, cyano, -NR4R5, -C (O) NR6R7, C1-C6 haloalkyl, C1-C6 haloalkoxy, -R8, -OCH2R8, C1-C6 alkoxy, C3-C8 cycloalkyl and C1-C6 alkyl, the alkyl substituent itself being optionally substituted by minus one substituent selected from cyano, -C (O) NR9R10, C1-C6 alkoxy and -NHC (O) R11, or R3 represents a 6-membered monocyclic aromatic heterocyclic group containing 1, 2, 3 or 4 selected ring heteroatoms independently of nitrogen, oxygen and sulfur, heterocyclic group which may be optionally substituted by at least one substituent selected from halogen, cyano, oxo, -NR4R5, -C (O) NR6R7, haloalkyl C1-C6, haloalkoxy C1-C6, -R8 , -OCH2R8, alkoxy C 1- C6, C3-C8 cycloalkyl and C1-C6 alkyl, the alkyl substituent itself being optionally substituted by at least one substituent selected from cyano, -C (O) NR9R10, C1-C6 alkoxy and -NHC (O) R11, or R3 represents a group of formula (II) ** Formula
