enQueue

#include<stdio.h>
#include<stdlib.h>
typedef struct data
{
    int a;
    struct data *next,*previous;
} data;
data *head=NULL;
data *tail=NULL;
void enQueue(int x)
{
    data *node=(data*)malloc(sizeof(data));
    node->a=x;
    node->next=NULL;
    node->previous=NULL;
    if(head==NULL)
    {
        head=node;
        tail=node;
        return;
    }
    node->previous=tail;
    tail->next=node;
    return;

}

int deQueue()
{
    data *temp=head;
    int x;
    if(head==NULL)
    {
        printf("no data!/n");
        return -1;
    }

    else if(temp->next==NULL)
    {
        x=temp->a;
        free(temp);
        head=NULL;
        tail=NULL;
        return x;

    }
    head=temp->next;
    x=temp->a;
    free(temp);
    head->previous=NULL;
    return x;

}
void print()
{
    data *temp=head;
    while(temp!=NULL)
    {
        printf("%d/n",temp->a);
        temp=temp->next;
    }
    printf("\n");
}
int main()
{
    int n1,n2,n3,n4,i,x,max=-1;
    scanf("%d",&n1);
    for(i=0; i<n1; i++)
    {
        scanf("%d",&n2);
        enQueue(n2);

    }
    scanf("%d",&n3);
    for(i=0; i<n3; i++)
    {
//        scanf("%d",&n4);
        x=deQueue();
        if(max<x)
        {
            max=x;
        }
    }
    print();
    printf("max :%d/n",max);


}