Compilare: main.c:10:1: warning: return type defaults to 'int' [-Wimplicit-int] main(){ ^~~~ main.c: In function 'main': main.c:11:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.in","r",stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:12:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.out","w",stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:13:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m);n--; ^~~~~~~~~~~~~~~~~~~~