t = +(*(a(#,#),b(#,#)),/(c(#,#),d(#,#))) size(t) = 7 computation of size(t) : '+' > '*' > > 'a' > > > # > > > size = 0 > > > # > > > size = 0 > > size = 1 > > 'b' > > > # > > > size = 0 > > > # > > > size = 0 > > size = 1 > size = 3 > '/' > > 'c' > > > # > > > size = 0 > > > # > > > size = 0 > > size = 1 > > 'd' > > > # > > > size = 0 > > > # > > > size = 0 > > size = 1 > size = 3 size = 7