foo.cc: In function 'void solve()':
foo.cc:27:17: error: 'reserve' was not declared in this scope
   27 |                 reserve(q.begin(), q.end());
      |                 ^~~~~~~
foo.cc:28:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |                 for(int i = 0; i < v.size(); ++i)
      |                                ~~^~~~~~~~~~
foo.cc:30:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |                 for(int i = 0; i < v.size(); ++i) {
      |                                ~~^~~~~~~~~~

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