foo.cc: In function 'std::string work(std::string)':
foo.cc:15:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |   for(int j=0;j<s[i].length();j++) {
      |               ~^~~~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:40:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |    while(i<str.length()-1&&str[i]==' ') i++;
      |          ~^~~~~~~~~~~~~~~
foo.cc:43:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |   while(i<str.length()-1&&str[i]==' ') i++;
      |         ~^~~~~~~~~~~~~~~
foo.cc:45:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |   while(i<str.length()-1&&str[i]!=' '&&str[i]!='!') {
      |         ~^~~~~~~~~~~~~~~

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