Compilare: main.c: In function 'main': main.c:6:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("100m.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:7:6: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("100m.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^~~~~~~~~~~~~~~