Compilare: user.c: In function ‘main’: user.c:4:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fmcm.in","r",stdin),freopen("fmcm.out","w",stdout),scanf("%d%d%d%d",&n,&m,&s,&d); ^ user.c:4:38: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fmcm.in","r",stdin),freopen("fmcm.out","w",stdout),scanf("%d%d%d%d",&n,&m,&s,&d); ^ user.c:4:67: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("fmcm.in","r",stdin),freopen("fmcm.out","w",stdout),scanf("%d%d%d%d",&n,&m,&s,&d); ^ user.c:6:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&i,&j,&l,&k),g[i][a[i]++]=j,g[j][a[j]++]=i,c[i][j]=l,o[i][j]=k,o[j][i]=-k; ^