Compilare: user.cpp: In function ‘std::vector<std::pair<int, int> > merge(std::vector<std::pair<int, int> >&, std::vector<std::pair<int, int> >&)’: user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < B.size(); ++i) ^ user.cpp:34:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < A.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:149:13: warning: unused variable ‘xx’ [-Wunused-variable] int xx, yy; ^ user.cpp:149:17: warning: unused variable ‘yy’ [-Wunused-variable] int xx, yy; ^ user.cpp: In function ‘bool solve(std::pair<int, int>, std::pair<int, int>, int)’: user.cpp:138:27: warning: ‘lo’ may be used uninitialized in this function [-Wmaybe-uninitialized] query(1, 1, n, lo, hi); ^ user.cpp:138:27: warning: ‘hi’ may be used uninitialized in this function [-Wmaybe-uninitialized]