answer.code: In function ‘int main()’:
answer.code:1938:23: error: expected primary-expression before ‘for’
 1938 | #define REP2(i, a, b) for (ll i = (a); i < (ll)(b); ++i)
      |                       ^~~
answer.code:1939:19: note: in expansion of macro ‘REP2’
 1939 | #define REP(i, n) REP2(i, 0, n)
      |                   ^~~~
answer.code:1937:43: note: in expansion of macro ‘REP’
 1937 | #define OVERLOADER(_1, _2, _3, NAME, ...) NAME
      |                                           ^~~~
answer.code:1940:18: note: in expansion of macro ‘OVERLOADER’
 1940 | #define rep(...) OVERLOADER(__VA_ARGS__, REP2, REP)(__VA_ARGS__)
      |                  ^~~~~~~~~~
answer.code:2195:9: note: in expansion of macro ‘rep’
 2195 |         rep(i, S) {
      |         ^~~
answer.code:2195:13: error: ‘i’ was not declared in this scope
 2195 |         rep(i, S) {
      |             ^
answer.code:1938:40: note: in definition of macro ‘REP2’
 1938 | #define REP2(i, a, b) for (ll i = (a); i < (ll)(b); ++i)
      |                                        ^
answer.code:1937:43: note: in expansion of macro ‘REP’
 1937 | #define OVERLOADER(_1, _2, _3, NAME, ...) NAME
      |                                           ^~~~
answer.code:2195:9: note: in expansion of macro ‘rep’
 2195 |         rep(i, S) {
      |         ^~~
answer.code:2200:5: error: expected primary-expression before ‘)’ token
 2200 |     );
      |     ^