Compilare: main.cpp: In function 'int main()': main.cpp:17:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for(i=0;i<s.size();i++) | ~^~~~~~~~~ main.cpp:23:7: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 23 | if(i!=s.size()-1) | ~^~~~~~~~~~~~ main.cpp:37:6: warning: statement has no effect [-Wunused-value] 37 | for(i;i<a.size();i++) | ^ main.cpp:37:9: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for(i;i<a.size();i++) | ~^~~~~~~~~