Compilare: user.c: In function ‘bfs’: user.c:10:5: warning: implicit declaration of function ‘memset’ [-Wimplicit-function-declaration] memset(a,-1,sizeof(a)); ^ user.c:10:5: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] user.c: In function ‘main’: user.c:32:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.in","r",stdin); ^ user.c:33:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.out","w",stdout); ^ user.c:34:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&N,&M,&S); ^ user.c:39:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&from,&to); ^