int main()
{
  int n,b[65535],c[65535],i,k;
  scanf("%d",&n);
  int a[n];
   for(i=0;i<n;i++)
  {
   a[i]=0;
  }
  
  
  scanf("%d %d",&b[0],&c[0]);
  a[b[0]]=a[b[0]]-1;
  a[c[0]]=a[c[0]]+1;
  for(k=0;;k++)
  {
     if(b[k]==0&&c[k]==0)
     break;
     else
     {
     scanf("%d %d",&b[k+1],&c[k+1]);
     a[b[k+1]]=a[b[k+1]]-1;
     a[c[k+1]]=a[c[k+1]]+1;
     }
  }
  for(i=0;i<n;i++)
  {
    if(a[i]==(n-1))
    {
      printf("%d",i);
      break;
    }
  }
   getchar();
   getchar();   
}
