Compilare: main.cpp: In function 'void solve()': main.cpp:24:18: 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=0;i<a.size();i++) { | ~^~~~~~~~~ main.cpp:37:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for(int i=0;i<a.size();i++) { | ~^~~~~~~~~