Compilare: user.cpp: In function ‘std::vector<std::pair<int, int> > nfp(std::pair<int, int>, std::vector<std::pair<int, int> >, std::vector<std::pair<int, int> >)’: user.cpp:26:58: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1, aux = (int) stk.size(); i < nfp.size(); i ++ ) { ^ user.cpp:30:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while( stk.size() > aux && ccw( nfp[stk[stk.size() - 2]], nfp[stk[stk.size() - 1]], nfp[i] ) >= 0 ) { ^ user.cpp:43:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while( stk.size() > aux && ccw( nfp[stk[stk.size() - 2]], nfp[stk[stk.size() - 1]], nfp[i] ) >= 0 ) { ^ user.cpp: In function ‘bool ipg(std::pair<int, int>, std::vector<std::pair<int, int> >)’: user.cpp:68:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < pg.size(); i ++ ) { ^ user.cpp: In function ‘int main()’: user.cpp:121:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < pts.size(); i ++ ) { ^ user.cpp:122:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = i + 1; j < pts.size(); j ++ ) { ^ user.cpp:130:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int k = 0; k < pg.size() && ok == true; k ++ ) { ^