foo.cc: In function 'void solve()':
foo.cc:32:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |                 for(int i = 0; i < v.size(); ++i)
      |                                ~~^~~~~~~~~~
foo.cc:34:34: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |                 for(int i = 0; i < v.size() - 1; ++i) {
      |                                ~~^~~~~~~~~~~~~~

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