Compilare: main.c: In function 'main': main.c:4:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("adunare.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:5:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("adunare.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^~~~~~~~~~~~~~~~~~~~~