foo.cc: In member function 'void vvector::merge(vvector&)':
foo.cc:20:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                 for(;i<num.size()&&j<b.num.size();)
      |                      ~^~~~~~~~~~~
foo.cc:20:37: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                 for(;i<num.size()&&j<b.num.size();)
      |                                    ~^~~~~~~~~~~~~
foo.cc:38:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |                 while(i<num.size())
      |                       ~^~~~~~~~~~~
foo.cc:40:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |                 while(j<b.num.size())
      |                       ~^~~~~~~~~~~~~

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