int search(List first,int key, int low, int high){
    int pivot;
    if(low <= high){
        pivot = (low + high) / 2;
        first.moveCursor(pivot);
        if(first.getCursor() == key){
            return pivot;
        }else if(key < first.getCursor()){
            return search(first, key, low, pivot-1);
        }else if(key > first.getCursor()){
            return search(first, key, pivot+1, high);
        }
    }
    else{
        return -1;
    }
}