Compilare: user.cpp: In function ‘void add(std::deque<int>, std::deque<int>)’: user.cpp:19:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= a.size() or i <= b.size() or t; ++i, t /= 10) ^ user.cpp:19:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= a.size() or i <= b.size() or t; ++i, t /= 10) ^