Compilare: user.c: In function ‘enqueue’: user.c:16:20: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] node* p = (node *)malloc(sizeof(node)); ^~~~~~ user.c:16:20: warning: incompatible implicit declaration of built-in function ‘malloc’ user.c:16:20: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’ user.c: In function ‘main’: user.c:79:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(ip, "%d%d", &n, &m); ^~~~~~~~~~~~~~~~~~~~~~~~~~ user.c:85:3: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(ip, "%d%d", &x, &y); ^~~~~~~~~~~~~~~~~~~~~~~~~~