Compilare: user.cpp: In function ‘int cost(std::__cxx11::string)’: user.cpp:25:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<S.length(); i++){ ^ user.cpp: In function ‘int main()’: user.cpp:80:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=1; i<=m && apm.size()!=n-1; i++){ ^