Compilare: main.cpp: In function 'int main()': main.cpp:12:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 12 | for(int i=0; i<a.size(); ++i) | ~^~~~~~~~~ main.cpp:18:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | for(int i=0; i<a.size(); ++i) | ~^~~~~~~~~ main.cpp:24:26: 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 i=a.size(); i<b.size(); ++i) | ~^~~~~~~~~