#include #include typedef struct{ int key; struct node *next; }node; node *head,*tail; void init_node(void) { head=(node*)malloc(sizeof(node)); tail=(node*)malloc(sizeof(node)); head->next=tail; tail->next=tail; } node *inputn(node *h) { int a; node *s; s=(node*)malloc(sizeof(node)); printf("Input Key Data :"); scanf("%d",&a); s->key=a; s->next=h->next; h->next=s; return s; } void deln(node *h) ..