Connections

Harshit and Aman, being in different halls, face connectivity issues very frequently. They each have arrays $a$ and $b$ containing $x$ & $y$ signals respectively. Signal $a_i$ can connect with signal $b_j$ only if $a_i=b_j$. Also, the connections shouldn't cross. Formally, if a connection exists between $a_i$ & $b_j$, then $a_k(k>i)$ can only connect with $b_l(l>j)$. Find out the **maximum** num