Compilare: main.c: In function 'main': main.c:21:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("dusman.in","r",stdin),freopen("dusman.out","w",stdout),scanf("%d%d%d",&n,&k,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:21:36: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("dusman.in","r",stdin),freopen("dusman.out","w",stdout),scanf("%d%d%d",&n,&k,&m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:21:69: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("dusman.in","r",stdin),freopen("dusman.out","w",stdout),scanf("%d%d%d",&n,&k,&m); ^~~~~~~~~~~~~~~~~~~~~~~~ main.c:23:9: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&i,&j),a[i][j]=a[j][i]=1; ^~~~~~~~~~~~~~~~~~~