Five circles $C_1, C_2, C_3, C_4, C_5$ with radi $ r_1 r_2, r_3, r_4, r_5. $ respectively $(r_1 < r_2 < r_3 < r_4 < r_5)$ be such that $C_1$ and $C_{i+1}$ touch each other externally for all $i = 1, 2, 3, 4. $ If all the five circles touch each of the two straight lines $ L_1$ and $L_2 $ and $r_1= 2$ and $r_5 = 32$, then $ r_3$ is equal to