Compilare: main.cpp: In function 'int trans(std::string)': main.cpp:86:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 86 | for (int i = 0; i < a.size(); i++) | ~~^~~~~~~~~~ main.cpp: In function 'std::string add(std::string, std::string)': main.cpp:109:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 109 | for (int i = 0; i < a.size(); i++) | ~~^~~~~~~~~~ main.cpp:113:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 113 | if (i <= b.size() - 1) | ~~^~~~~~~~~~~~~~~ main.cpp: In function 'std::string prod(std::string, std::string)': main.cpp:156:9: warning: unused variable 'bs' [-Wunused-variable] 156 | int bs = b.size(); | ^~