Compilare: user.cpp: In function ‘void df(int)’: user.cpp:24:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<v[i].size();++j) ^ user.cpp: In function ‘int main()’: user.cpp:52:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<euler.size();++i) ^ user.cpp:56:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<euler.size();++i) ^ user.cpp:68:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=1;1<<i<=euler.size();++i) ^