Compilare: user.c: In function ‘readd’: user.c:21:7: warning: implicit declaration of function ‘calloc’ [-Wimplicit-function-declaration] paux=calloc(1,sizeof(struct nod)); ^ user.c:21:12: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] paux=calloc(1,sizeof(struct nod)); ^ user.c: In function ‘visit’: user.c:47:12: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] paux=calloc(1,sizeof(struct nod)); ^ user.c: In function ‘readd’: user.c:16:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in","rt",stdin); ^ user.c:17:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out","wt",stdout); ^ user.c:18:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.c:20:12: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] { scanf("%d%d",&a,&b); ^