Compilare: user.cpp: In function ‘void make_graph(int)’: user.cpp:37:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < dv.size(); i++) ^ user.cpp:38:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < dv.size(); j++) ^ user.cpp: In function ‘int main()’: user.cpp:53:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("divisorgraph.in", "r", stdin); ^ user.cpp:54:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("divisorgraph.out", "w", stdout); ^ user.cpp:65:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &T); ^ user.cpp:68:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:80:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^