# get the coefficients of polynomial of several variables?

Consider that I have a polynomial with n variables x1,x2,...,xn and want to get the coefficient of that polynomial. For example I can have:
x1+2*x1*x5^2+3*x1^2*x4-5*x2*x5^2+1/2*x2*x3+x6^2*x7*x8+9*x3*x9^3

I would like to ask Sage to give coefficient for the polynomial with variables x1..x9 and the result should be something like this: coefficient,(exponent of x1..x9); 1,(1,0,0,0,0,0,0,0,0); 2,(1,0,0,0,2,0,0,0,0); 3,(2,0,0,1,0,0,0,0,0); -5,(0,1,0,0,2,0,0,0,0); 1/2,(0,1,1,0,0,0,0,0,0); 1,(0,0,0,0,0,2,1,1); 9,(0,0,1,0,0,0,0,0,3)

How can I achieve this?