Compilare: main.c: In function 'main': main.c:13:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.in","r",stdin),freopen("chernel.out","w",stdout),scanf("%d%d",&n,&m),--n; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:13:34: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.in","r",stdin),freopen("chernel.out","w",stdout),scanf("%d%d",&n,&m),--n; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:13:68: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("chernel.in","r",stdin),freopen("chernel.out","w",stdout),scanf("%d%d",&n,&m),--n; ^~~~~~~~~~~~~~~~~~~