Compilare: user.cpp: In function ‘int main()’: user.cpp:32:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();++i) ^ user.cpp:47:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();++i) ^ user.cpp:59:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=beg;i<v.size()-1;++i) ^