G is an N atom or a group of the formula (a) ##STR3## where R0 is hydrogen, halogen, e.g. chlorine or fluorine, or cyano, X1 is hydrogen, halogen, e.g. chlorine or fluorine, or a group of the formula (b) ##STR4## where Ra has one of the meanings of R and A0 has one of the meanings of A and is preferably fluorine,