foo.cc: In function 'std::string product(int, int)':
foo.cc:88:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |         for (int i=0;i<nums.size();i++)
      |                      ~^~~~~~~~~~~~
foo.cc:56:13: warning: unused variable 'temp' [-Wunused-variable]
   56 |         int temp = 0;
      |             ^~~~

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