foo.cc: In function ‘void merge(const std::vector<int>&, const std::vector<int>&, std::vector<int>&)’:
foo.cc:6:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    6 |     while(i<v1.size()&&j<v2.size()){
      |           ~^~~~~~~~~~
foo.cc:6:25: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    6 |     while(i<v1.size()&&j<v2.size()){
      |                        ~^~~~~~~~~~
foo.cc:12:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   12 |     while(i<v1.size())
      |           ~^~~~~~~~~~
foo.cc:14:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   14 |     while(j<v2.size())
      |           ~^~~~~~~~~~