Language: C

#include<stdio.h>
#include<stdlib.h>
struct node{int n;node *np,*pp;};
node *fp=NULL,*ep,*n;
int N,t;
char cmd[15];

void del(node*dp)
{
	node *nnp=dp->np;
	node *npp=dp->pp;
	npp->np=nnp;
	nnp->pp=npp;
	free(dp);
}

int main()
{
	scanf("%d\n",&N);
	for(;N--;)
	{
		scanf("%s",cmd);
		if(cmd[0]=='i')
		{
			scanf("%d\n",&t);
			node *tp=(node*)malloc(sizeof(node));
			tp->n=t;
			if(fp==NULL)
			{
				tp->np=tp->pp=tp;
				fp=tp;
				ep=tp;
				tp->np=fp;
			}
			else
			{
				tp->np=fp;
				fp->pp=ep->np=tp;
				tp->pp=ep;
				fp=tp;
			}
		}
		else
		{
			if(cmd[6]=='F')
			{
				node *nfp=fp;
				fp=fp->np;
				del(nfp);
			}
			else if(cmd[6]=='L')
			{
				node *nep=ep;
				ep=ep->pp;
				del(nep);
			}
			else
			{
				scanf("%d\n",&t);
				for(n=fp;n->n!=t;n=n->np);
				if(n==fp)
					fp=fp->np;
				if(n==ep)
					ep=ep->pp;
				del(n);
			}
		}
	}
	for(n=fp,t=1;t||n!=fp;n=n->np)
		t=!printf("%d%c",n->n,n->np==fp?'\n':' ');
	return 0;
}

Compiler output:
main.c:3:19: error: unknown type name 'node'
    3 | struct node{int n;node *np,*pp;};
      |                   ^~~~
main.c:4:1: error: unknown type name 'node'; use 'struct' keyword to refer to the type
    4 | node *fp=NULL,*ep,*n;
      | ^~~~
      | struct 
main.c:8:10: error: unknown type name 'node'
    8 | void del(node*dp)
      |          ^~~~
main.c: In function 'main':
main.c:26:25: error: unknown type name 'node'; use 'struct' keyword to refer to the type
   26 |                         node *tp=(node*)malloc(sizeof(node));
      |                         ^~~~
      |                         struct 
main.c:26:35: error: 'node' undeclared (first use in this function)
   26 |                         node *tp=(node*)malloc(sizeof(node));
      |                                   ^~~~
main.c:26:35: note: each undeclared identifier is reported only once for each function it appears in
main.c:26:40: error: expected expression before ')' token
   26 |                         node *tp=(node*)malloc(sizeof(node));
      |                                        ^
main.c:27:27: error: request for member 'n' in something not a structure or union
   27 |                         tp->n=t;
      |                           ^~
main.c:30:35: error: request for member 'np' in something not a structure or union
   30 |                                 tp->np=tp->pp=tp;
      |                                   ^~
main.c:30:42: error: request for member 'pp' in something not a structure or union
   30 |                                 tp->np=tp->pp=tp;
      |                                          ^~
main.c:33:35: error: request for member 'np' in something not a structure or union
   33 |                                 tp->np=fp;
      |                                   ^~
main.c:37:35: error: request for member 'np' in something not a structure or union
   37 |                                 tp->np=fp;
      |                                   ^~
main.c:38:35: error: request for member 'pp' in something not a structure or union
   38 |                                 fp->pp=ep->np=tp;
      |                                   ^~
main.c:38:42: error: request for member 'np' in something not a structure or union
   38 |                                 fp->pp=ep->np=tp;
      |                                          ^~
main.c:39:35: error: request for member 'pp' in something not a structure or union
   39 |                                 tp->pp=ep;
      |                                   ^~
main.c:47:39: error: 'nfp' undeclared (first use in this function); did you mean 'fp'?
   47 |                                 node *nfp=fp;
      |                                       ^~~
      |                                       fp
main.c:48:38: error: request for member 'np' in something not a structure or union
   48 |                                 fp=fp->np;
      |                                      ^~
main.c:49:33: error: implicit declaration of function 'del' [-Wimplicit-function-declaration]
   49 |                                 del(nfp);
      |                                 ^~~
main.c:53:39: error: 'nep' undeclared (first use in this function); did you mean 'ep'?
   53 |                                 node *nep=ep;
      |                                       ^~~
      |                                       ep
main.c:54:38: error: request for member 'pp' in something not a structure or union
   54 |                                 ep=ep->pp;
      |                                      ^~
main.c:60:43: error: request for member 'n' in something not a structure or union
   60 |                                 for(n=fp;n->n!=t;n=n->np);
      |                                           ^~
main.c:60:53: error: request for member 'np' in something not a structure or union
   60 |                                 for(n=fp;n->n!=t;n=n->np);
      |                                                     ^~
main.c:62:46: error: request for member 'np' in something not a structure or union
   62 |                                         fp=fp->np;
      |                                              ^~
main.c:64:46: error: request for member 'pp' in something not a structure or union
   64 |                                         ep=ep->pp;
      |                                              ^~
main.c:69:34: error: request for member 'np' in something not a structure or union
   69 |         for(n=fp,t=1;t||n!=fp;n=n->np)
      |                                  ^~
main.c:70:35: error: request for member 'n' in something not a structure or union
   70 |                 t=!printf("%d%c",n->n,n->np==fp?'\n':' ');
      |                                   ^~
main.c:70:40: error: request for member 'np' in something not a structure or union
   70 |                 t=!printf("%d%c",n->n,n->np==fp?'\n':' ');
      |                                        ^~