#include <stdio.h>
#include<malloc.h>
typedef struct node{
	char Elem;
	struct node *next;
}Lnode;

void main()
{
	char k;
	int start,length,len=0;
	Lnode *s,*l,*p,*q,*tail;
	s =(Lnode*) malloc(sizeof (Lnode));
	s->Elem=0;
	s->next=NULL;
	printf("Input the first string:");
	k=getchar();
	while(k!=(char)(10))
	{
		p =(Lnode*) malloc(sizeof (Lnode));
		
		p->Elem=k;
		p->next=NULL;
		len++;

		if (s->next==NULL)
		{
			s->next = p;
			tail=p;
		}
		else
		{tail->next=p;tail=p;}
		k=getchar();
	}

	printf("\nInput the start pos and length:");
	scanf("%d %d",&start,&length);
	if(start>len||start+length>len)printf("Error!");
	else{

	}
}