Compilare: main.cpp: In function 'int main()': main.cpp:27:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 27 | for(int i=0;i<a.size();++i) | ~^~~~~~~~~ main.cpp:29:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | for(int i=0;i<b.size();++i) | ~^~~~~~~~~ main.cpp:38:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | for(int i=0;i<a.size();++i) | ~^~~~~~~~~ main.cpp:41:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 41 | for(int i=0;i<b.size();++i) | ~^~~~~~~~~ main.cpp:43:14: warning: unused variable 'x' [-Wunused-variable] 43 | char x=b[i]; | ^