Compilare: main.c: In function 'main': main.c:61:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.in", "rt", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:62:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.out", "wt", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:65:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &info.n_vertices, &n_edges); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:79:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &a, &b, &d); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~