Compilare: user.cpp: In function ‘void valid(std::vector<char>)’: user.cpp:15:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ~^~~~~~~~~ user.cpp:15:5: warning: this ‘for’ clause does not guard... [-Wmisleading-indentation] for(int i=0;i<v.size();i++) ^~~ user.cpp:52:9: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the ‘for’ if(!s.empty()) ^~