Compilare: user.c: In function ‘main’: user.c:12:27: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] a[c&~(1<<i-2)]=0; ^ user.c:8:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("coins.in","r",stdin),freopen("coins.out","w",stdout),scanf("%d",&m),memset(a,-1,sizeof(a)); ^ user.c:8:42: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("coins.in","r",stdin),freopen("coins.out","w",stdout),scanf("%d",&m),memset(a,-1,sizeof(a)); ^ user.c:8:72: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("coins.in","r",stdin),freopen("coins.out","w",stdout),scanf("%d",&m),memset(a,-1,sizeof(a)); ^ user.c:32:18: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&b[i]); ^