/in/foo.cc: In function 'int matrixScore(std::vector<std::vector<int> >&)':
/in/foo.cc:9:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<A.size(); i++){
                  ~^~~~~~~~~
/in/foo.cc:11:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j=0; j<A[i].size(); j++){
                          ~^~~~~~~~~~~~
/in/foo.cc:19:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=1; i<A[0].size(); i++){
                  ~^~~~~~~~~~~~
/in/foo.cc:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0; j<A.size(); j++){
                      ~^~~~~~~~~
/in/foo.cc:25:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if(2*num>A.size()){
            ~~~~~^~~~~~~~~
/in/foo.cc:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j=0; j<A.size(); j++){
                          ~^~~~~~~~~
/in/foo.cc:35:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<A.size(); i++){
                  ~^~~~~~~~~
/in/foo.cc:36:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=1; j<=A[i].size(); j++){
                      ~^~~~~~~~~~~~~