Compilare: user.cpp: In function ‘int main()’: user.cpp:73:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0, l = 1; k < pol.size(); ++k, l = (++l) % pol.size()) { ^ user.cpp:73:74: warning: operation on ‘l’ may be undefined [-Wsequence-point] for (int k = 0, l = 1; k < pol.size(); ++k, l = (++l) % pol.size()) { ^