Compilare: user.cpp: In function ‘int main()’: user.cpp:20:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); i++) { ^ user.cpp:26:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == a.size() - 1) { ^ user.cpp:34:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < 1000 && i < rez.size(); i++) ^ user.cpp: In function ‘void pref()’: user.cpp:43:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < a.size(); i++) { ^