Compilare: main.cpp: In function 'int main()': main.cpp:28:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | for (int i = 0; i < a.size(); ++i) { | ~~^~~~~~~~~~ main.cpp:34:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for (int i = 0; i < a.size(); ++i) { | ~~^~~~~~~~~~ main.cpp:39:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 39 | for (int i = a.size(); i < b.size(); ++i) { | ~~^~~~~~~~~~