Compilare: user.c: In function ‘main’: user.c:41:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:42:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:44:5: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hu %hu %hu %hu", &n, &m, &x, &y); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:47:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hu %hu", &u, &v); ^~~~~~~~~~~~~~~~~~~~~~~~