the schubert polynomials and key polynomials form two important bases for the polynomial ring. schubert and key polynomials are the​``bottom layers” of grothendieck and lascoux polynomials, two inhomogeneous polynomials. in this talk, we look at their​``top layers”. we develop a diagrammatic way to compute the degrees and the leading monomials of these top layers. finally, we describe the hilbert series of the space spanned by these top layers, involving a classical $q$-analogue of the bell numbers.