Compilare: user.cpp: In member function ‘void RMQ::buildMatrix()’: user.cpp:23:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int d = 0; d < matrix.front().size() - 1; d++) { ^ user.cpp:24:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < matrix.size(); i++) { ^ user.cpp:25:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (d >= matrix[i].size()) { ^ user.cpp:30:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos < matrix.size() && matrix[pos].size() > d) { ^ user.cpp:30:57: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos < matrix.size() && matrix[pos].size() > d) { ^ user.cpp: In function ‘int main()’: user.cpp:56:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rmq.in", "r", stdin); ^ user.cpp:57:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rmq.out", "w", stdout); ^ user.cpp:59:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:64:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^ user.cpp: In member function ‘void RMQ::read()’: user.cpp:17:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &row.front()); ^