Compilare: main.cpp: In function 'void addstring(int)': main.cpp:25:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 25 | for(int i=0;i<s.size();i++) | ~^~~~~~~~~ main.cpp:37:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | if(i+1==s.size()) | ~~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:88:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 88 | for(int i=0;i<a.size();i++) | ~^~~~~~~~~