COde is here:
#include "stdio.h"
long x[1000],y[1000];
int que[1000],pare[1000],path[1000],c[1000];

int main()
{
    int n,i,j,curret,count,temp,address;

    scanf("%d",&n);

    for(i=1;i<=n;i++)
    {
        c[i]=0;
        scanf("%ld%ld",&x[i],&y[i]);
    }
    scanf("%ld%ld%ld",&address,&x[0],&y[0]);
    que[0]=0;
    curret=0;
    count=1;
    while(curret<count)
    {
        if(x[que[curret]]==address||y[que[curret]]==address)
break;
        for(i=1;i<=n;i++)
        {
            if(c[i]==0)
            {
                if((x[i]==x[que[curret]])||(x[i]==y
[que[curret]]))
                {
                   que[count]=i;
                   pare[i]=que[curret];
                   c[i]=1;
                   count++;
                 }
            }
        }
        curret++;
    }
    if(x[que[curret]]==address||y[que[curret]]==address)
    {
        count=0;
        temp=que[curret];
        while(1)
        {
            if(temp==0) break;
             count++;
             path[count]=temp;
             temp=pare[temp];
         }
      printf("%ld\n",count);
      for(j=count;j>=1;j--)
      {
        printf("%d\n",path[j]);
      }

    }
    else
        printf("IMPOSSIBLE\n");

    return 0;
}