Wrong Answer
/in/foo.cc: In function 'void insert(arr)':
/in/foo.cc:22:12: warning: operation on 'sz' may be undefined [-Wsequence-point]
nxt[sz] = ++sz;
^~~~
/in/foo.cc: In function 'void insert(arr)':
/in/foo.cc:22:12: warning: operation on 'sz' may be undefined [-Wsequence-point]
nxt[sz] = ++sz;
^~~~
