foo.cc: In function 'void exchange(std::vector<int>&, std::vector<int>&)':
foo.cc:24:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |  for (int i = 0; i < b.size(); i++)a[i] = b[i];
      |                  ~~^~~~~~~~~~
foo.cc:26:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |  for (int i = 0; i < c.size(); i++)b[i] = c[i];
      |                  ~~^~~~~~~~~~
foo.cc: In function 'void Trav(std::vector<int>&)':
foo.cc:31:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |  for (int i = 0; i < b.size(); i++)
      |                  ~~^~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:49:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   49 |  for (int i = 0; i < a.size() - 1; i++)
      |                  ~~^~~~~~~~~~~~~~
foo.cc:52:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   52 |   for (int j = i + 1; j < a.size(); j++)
      |                       ~~^~~~~~~~~~
foo.cc:56:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |  for (int i = 0; i < a.size(); i++)
      |                  ~~^~~~~~~~~~

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