Some help or advice with this P-adic expansion problem would be much appreciated. Somewhat different to what I am used to and what I have seen, so I am having some problems manipulating it.

Find the first three digits a0, a1, a2 in the 3 adic expansion a0 + a13+a2(3^2) with ai an element of {0,1,2} of the two square roots of 7 in Q3