#include <iostream>
using namespace std;
#include <cstdio>
struct node
{
int i;
node * nxt;
}*head,*a;
int main()
{
int n;
// cout<<"yes";
head=new node;
head->i=10;
a=head;
for(int j=0;j<9;j++)
{
node *ptr=new node;
// cout<<"\n enter value :";
cin>>ptr->i;
a->nxt=ptr;
a=ptr;
}
a->nxt=NULL;
a=head;
cout<<"\n before....";
for(int j=0;j<10;j++)
{
cout<<a->i<<"->";
a=a->nxt;
}
cout<<"\n after...";
node *s,*t,*u;
a=head;
while(a->nxt!=NULL)
{
// cout<<"yes";
u=a->nxt;
//cout<<"yes";
s=(a->nxt)->nxt;
if(a==NULL||u==NULL||s==NULL)
break;
t=s->nxt;
//cout<<u->i<<s->i<<t->i<<endl;
a->nxt=t;
u->nxt=t->nxt;
t->nxt=s;
s->nxt=u;
a->nxt=t;
a=u;
//cout<<u->i<<s->i<<t->i<<endl;
};
a=head;
while(a!=NULL)
{
cout<<a->i<<"->";
a=a->nxt;
}
cin>>n;
}
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