void Getnext(int next[],String t)

{

   int j=0,k=-1;

   next[0]=-1;

   while(j<t.length-1)

   {

      if(k == -1 || t[j] == t[k])

      {

         j++;k++;

         next[j] = k;

      }

      else k = next[k];

   }