foo.cc: In function 'int main()':
foo.cc:6:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    6 |  for(int i=0;i<a.length();i++){
      |              ~^~~~~~~~~~~
foo.cc:8:17: 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< a.length();j++){
      |                ~^~~~~~~~~~~~
foo.cc:16:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |    for(int j=0;j< a.length();j++){
      |                ~^~~~~~~~~~~~
foo.cc:24:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |    for(int j=0;j< a.length();j++){
      |                ~^~~~~~~~~~~~

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