foo.cc: In constructor 'Biglnt::Biglnt(int, int)':
foo.cc:21:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |    for (int j = 0;j < a.size();j++)
      |                   ~~^~~~~~~~~~
foo.cc:25:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   25 |      if (j == a.size() - 1)
      |          ~~^~~~~~~~~~~~~~~

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