Compilare: main.cpp: In function 'int main()': main.cpp:136:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 136 | for(j=0; j<s.size(); j++) | ~^~~~~~~~~ main.cpp:149:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 149 | for(i=0; i<s.size(); i++) | ~^~~~~~~~~