foo.cc: In function 'int main()':
foo.cc:7:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    7 |         for(int i=1;i<a.size();i++)
      |                     ~^~~~~~~~~
foo.cc:8:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |                 for(int j=0;j+i<a.size();j++)
      |                             ~~~^~~~~~~~~

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