Compilare: user.cpp: In function ‘int main()’: user.cpp:32:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < D[0].size(); ++i) ^ user.cpp:39:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < D[0].size(); ++i) ^ user.cpp:15:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("conserve.in","r",stdin); ^ user.cpp:16:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("conserve.out","w",stdout); ^ user.cpp:18:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &p); ^ user.cpp:22:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &A[i]); int x = A[i]; ^