Compilare: user.cpp: In function ‘long long int factorial()’: user.cpp:13:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=s.size();i++) ^ user.cpp:15:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:46:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int it=0;it<= s.size()-1;it++) ^