Compilare: main.cpp: In function 'int main()': main.cpp:30:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | for(int i = 0; i < a.size(); i ++) | ~~^~~~~~~~~~ main.cpp:44:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 44 | for(int i = 0; i < a.size(); i ++) | ~~^~~~~~~~~~ main.cpp:56:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 56 | for(int i = a.size(); i < b.size(); i ++) | ~~^~~~~~~~~~