Compilare: user.c: In function ‘main’: user.c:15:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in","r",stdin),freopen("sortnet.out","w",stdout),scanf("%d%d\n",&n,&m); ^ user.c:15:44: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in","r",stdin),freopen("sortnet.out","w",stdout),scanf("%d%d\n",&n,&m); ^ user.c:15:76: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in","r",stdin),freopen("sortnet.out","w",stdout),scanf("%d%d\n",&n,&m); ^ user.c:18:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("<%d,%d> ",&a,&b),a--,b--,g[i][a]=b,g[i][b]=a; ^