Compilare: main.c: In function 'main': main.c:80:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen(FIN, "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~ main.c:82:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT, "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:84:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &nodes, &edges); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:88:10: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^~~~~~~~~~~~~~~~~~~~~~