foo.cc: In function 'int Solve(std::vector<std::vector<int> >&)':
foo.cc:11:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     for (int i = 0; i < v.size(); i++)
      |                     ~~^~~~~~~~~~
foo.cc:13:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |         for (int j = 0; j < v[i].size(); j++)
      |                         ~~^~~~~~~~~~~~~
foo.cc:18:46: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |                 if (i + x[k] < 0 || i + x[k] >= v.size() || j + y[k] < 0 || j + y[k] >= v[i].size())
      |                                     ~~~~~~~~~^~~~~~~~~~~
foo.cc:18:86: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |                 if (i + x[k] < 0 || i + x[k] >= v.size() || j + y[k] < 0 || j + y[k] >= v[i].size())
      |                                                                             ~~~~~~~~~^~~~~~~~~~~~~~

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