Compilare: user.cpp: In function ‘void delete_duplicates(std::vector<std::pair<int, int> >&)’: user.cpp:18:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < traps.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:91:23: warning: ‘x1’ may be used uninitialized in this function [-Wmaybe-uninitialized] x = x1, y = y1; ^ user.cpp:91:23: warning: ‘y1’ may be used uninitialized in this function [-Wmaybe-uninitialized]