Compilare: user.cpp: In function ‘int main()’: user.cpp:23:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < q[2].size(); ++i) { ^ user.cpp:28:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < q[3].size(); ++i) { ^ user.cpp:34:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < q[1].size(); ++i) { ^ user.cpp:39:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[i].size(); ++j) { ^