public static void insertsort (int a[], int left, int right) {
      int i,k,t;
      for (k = left+1 ; k <= right; k++) {
        t = a[k] ;
        i = k;
        while ( a[i-1] > t ) {
           a[i] = a[i-1];
           if (--i == left) break;
        }
        a[i] = t;
      } // end k
   } // end insertsort