Compilare: main.cpp: In function 'int main()': main.cpp:28:18: 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:30:18: 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<b.size();++i) | ~^~~~~~~~~ main.cpp:39:18: 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=0;i<a.size();++i) | ~^~~~~~~~~ main.cpp:42:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 42 | for(int i=0;i<b.size();++i) | ~^~~~~~~~~ main.cpp:44:14: warning: unused variable 'x' [-Wunused-variable] 44 | char x=b[i]; | ^