foo.cc: In function 'int main()':
foo.cc:14:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |     for(int i=1;i<=a.size()-1;i++)
      |                 ~^~~~~~~~~~~~
foo.cc:21:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     for(int i=0;i<=a.size()-2;i++)
      |                 ~^~~~~~~~~~~~
foo.cc:6:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    6 |  freopen("1.txt","r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~

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