[QUE/QFT-13001] QFT-PROBLEM

$\newcommand{\matrixelement}[3]{\langle#1|#2|#3\rangle}$
Use Wick's theorem to evaluate the following free field time ordered operator product \[T\big(:\phi^4(x):\ :\phi^4(y):\big)\] and write it as a sum of normal ordered products and in terms of \(\Delta(x-y)=\matrixelement{0}{T(\phi(x)\phi(y))}{0}\). Which term(s), if any, will contribute to \(\pi-\pi\) scattering, if the field \(\phi(x)\) represents neutral pion field.