/in/foo.cc:99:6: error: expected unqualified-id before 'delete'
   99 | void delete(int n) {
      |      ^~~~~~
/in/foo.cc: In function 'void next()':
/in/foo.cc:297:16: error: a function-definition is not allowed here before '{' token
  297 | void next_op() {
      |                ^
/in/foo.cc:336:16: error: a function-definition is not allowed here before '{' token
  336 | void prev_op() {
      |                ^
/in/foo.cc:350:24: error: a function-definition is not allowed here before '{' token
  350 | void next_op_correct() {
      |                        ^
/in/foo.cc:380:14: error: a function-definition is not allowed here before '{' token
  380 | void solve() {
      |              ^
/in/foo.cc:424:9: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
  424 | int main() {
      |         ^~
/in/foo.cc:424:9: note: remove parentheses to default-initialize a variable
  424 | int main() {
      |         ^~
      |         --
/in/foo.cc:424:9: note: or replace parentheses with braces to value-initialize a variable
/in/foo.cc:424:12: error: a function-definition is not allowed here before '{' token
  424 | int main() {
      |            ^
/in/foo.cc:427:2: error: expected '}' at end of input
  427 | }
      |  ^
/in/foo.cc:227:13: note: to match this '{'
  227 | void next() {
      |             ^
/in/foo.cc:378:6: warning: unused variable 'buffer' [-Wunused-variable]
  378 | char buffer[2000000]; // 插入缓冲区
      |      ^~~~~~