foo.cc: In member function 'Wint& Wint::check()':
foo.cc:21:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for (int i = 1; i < size(); ++i) {
      |                         ~~^~~~~~~~
foo.cc: In function 'Wint& operator+=(Wint&, const Wint&)':
foo.cc:80:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   80 |     for (int i = 0; i != b.size(); ++i)a[i] += b[i];
      |                     ~~^~~~~~~~~~~
foo.cc: In function 'Wint& operator-=(Wint&, Wint)':
foo.cc:90:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   90 |     for (int i = 0; i != b.size(); a[i] -= b[i], ++i)
      |                     ~~^~~~~~~~~~~
foo.cc: In function 'Wint operator*(const Wint&, const Wint&)':
foo.cc:110:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |     for (int i = 0; i != a.size(); ++i)
      |                     ~~^~~~~~~~~~~
foo.cc:111:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  111 |         for (int j = 0; j != b.size(); ++j)
      |                         ~~^~~~~~~~~~~

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