'%(),:=acdeginpstx
Let's try this without the l or o.
Since this has been cracked, the intended solution:
cat(diag(diag((a=scan()))%x%diag((a==a):a)),sep=''). diag is an interesting function, that can be used in three different ways. When presented with a single integer (diag(n)), it creates a NxN matrix with 1 on the diagonal. When presented with a vector (diag(1:n)), it creates an NxN matrix with the vector on the diagonal. When presented with a matrix (diag(diag(n))), it returns the diagonal as a vector. %x% computed the Kronecker product of two matrices, where each element in matrix 1 is multiplied with each element in matrix 2 separately. Doing this with a length n identity matrix and a 1:n diagonal matrix, creates a length n^2 diagonal matrix with 1:n repeated n times. diag extracts that again, and cat prints.