Compilare: user.c: In function ‘main’: user.c:32:4: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!c[i]) ^ user.c:24:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin),freopen("biconex.out","w",stdout),scanf("%d%d",&n,&m); ^ user.c:24:41: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin),freopen("biconex.out","w",stdout),scanf("%d%d",&n,&m); ^ user.c:24:73: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in","r",stdin),freopen("biconex.out","w",stdout),scanf("%d%d",&n,&m); ^ user.c:26:11: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a[i],&b[i]),w[a[i]]++,w[b[i]]++; ^