Compilare: main.c: In function 'main': main.c:79:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen(FIN, "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~ main.c:81:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT, "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:83:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &nodes, &edges); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:87:10: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^~~~~~~~~~~~~~~~~~~~~~