Compilare: main.cpp: In function 'int main()': main.cpp:19:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 19 | for(i=2;i<a.size();i++) | ~^~~~~~~~~ main.cpp:10:9: warning: unused variable 'n' [-Wunused-variable] 10 | int n,i,j,k; | ^ main.cpp:10:13: warning: unused variable 'j' [-Wunused-variable] 10 | int n,i,j,k; | ^ main.cpp:12:10: warning: variable 'd' set but not used [-Wunused-but-set-variable] 12 | char d,c; | ^ main.cpp:12:12: warning: variable 'c' set but not used [-Wunused-but-set-variable] 12 | char d,c; | ^