Good morning p45cal
thanks for your help but on my excel 2021 prof plus i get an error ...

=_xlfn.LAMBDA(_xlpm.vals;_xlpm.groups;_xlpm.group;LET(b;MAX(_xlfn.BYROW(--(MATR.TRASPOSTA(_xlpm.vals)=FILTRO(_xlpm.vals;_xlpm.groups=_xlpm.group));_x lfn.LAMBDA(_xlpm.a;SOMMA(_xlpm.a))));SE.ERRORE(SE(b>1;b;0);0)))

...could it be that LAMDA and LET are only available on office 365 ?