/in/foo.cc: In lambda function:
/in/foo.cc:122:10: error: expected unqualified-id before '[' token
     auto [q, r] = v[i++];
          ^
/in/foo.cc:124:26: error: 'r' was not declared in this scope
     for (int j = 1; j <= r; ++j) dfs(i, s *= q, p *= q - (j == 1));
                          ^
/in/foo.cc:124:46: error: 'q' was not declared in this scope
     for (int j = 1; j <= r; ++j) dfs(i, s *= q, p *= q - (j == 1));
                                              ^