Compilare: main.cpp: In function 'int main()': main.cpp:55:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 55 | for (i = 0; i < a.size(); ++i) | ~~^~~~~~~~~~ main.cpp:57:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 57 | for (i = 0; i < b.size(); ++i) | ~~^~~~~~~~~~ main.cpp:68:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 68 | for (i = 0, j = 0; i < a.size(); ++i) | ~~^~~~~~~~~~