// デクリメント演算子
    std::map< unsigned int, unsigned int >::iterator it = data.end();
    --it;
    std::cout << it->first << ", " << it->second << std::endl;

    // std::advance関数（<iterator>ヘッダをインクルード）
    it = data.end();
    std::advance( it, -1 );
    std::cout << it->first << ", " << it->second << std::endl;

    // reverse_iterator, rbegin
    std::map< unsigned int, unsigned int >::reverse_iterator rit = data.rbegin();
    std::cout << rit->first << ", " << rit->second << std::endl;