Compilare: main.c: In function 'main': main.c:29:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("2sat.in","r",stdin),freopen("2sat.out","w",stdout),scanf("%d%d",&n,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:29:31: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("2sat.in","r",stdin),freopen("2sat.out","w",stdout),scanf("%d%d",&n,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:29:62: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("2sat.in","r",stdin),freopen("2sat.out","w",stdout),scanf("%d%d",&n,&m); ^~~~~~~~~~~~~~~~~~~ main.c:31:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",a+i,b+i); ^~~~~~~~~~~~~~~~~~~~~