foo.cc: In function 'void bfs(int, std::vector<int>, int)':
foo.cc:27:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   27 |     if(step==M.size()&&a[0]!=0&&Sum(a,M.size())%k==0)
      |        ~~~~^~~~~~~~~~
foo.cc:34:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |         for(int i=0;i<M.size();i++)
      |                     ~^~~~~~~~~

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