Quicksort (int data[],int left,int right) {
   int mid,tmp,i,j;
   

   i = left;
   j = right;
   mid = data[(left + right)/2];
   do {
        while(data[i] < mid)
           i++;
       while(mid < data[j])
           j--;
       if (i <= j) {
           tmp = data[i];
           data[i] = data[j];
           data[j] = tmp;
           i++;
           j--;
       }
   } while (i <= j);
   if (left < j) Quicksort(data,left,j);
   if (i < right) Quicksort(data,i,right);
}