answer.code: In function ‘bool dfs(int, ull, ull)’:
answer.code:89:9: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   89 | int main()
      |         ^~
answer.code:89:9: note: remove parentheses to default-initialize a variable
   89 | int main()
      |         ^~
      |         --
answer.code:89:9: note: or replace parentheses with braces to value-initialize a variable
answer.code:90:1: error: a function-definition is not allowed here before ‘{’ token
   90 | {
      | ^
answer.code:98:2: error: expected ‘}’ at end of input
   98 | }
      |  ^
answer.code:80:1: note: to match this ‘{’
   80 | {
      | ^