class program
    {
    define halfturn()
        {
        turnleft();
        turnleft();
        }
    define turnright()
        {
        iterate( 3 )
            turnleft();
        }
    define caminaAPared()
        {
        while( frontIsClear )
            move();
        }
    define leftmove()
        {
        turnleft();
        move();
        }
    define buscaCentro()
        {
        if( frontIsClear )
            {
            move();
            move();
            buscaCentro();
            move();
            }
        else
            halfturn();
        }
    define bajaCalle()
        {
        caminaAPared();
        halfturn();
        while( leftIsBlocked && frontIsClear )
            move();
        turnleft();
        }
    define colocaCentro()
        {
        turnleft();
        caminaAPared();
        halfturn();
        buscaCentro();
        putbeeper();
        }
    program()
        {
        colocaCentro();
        bajaCalle();
        while( frontIsClear )
            {
            move();
            colocaCentro();
            bajaCalle();
            }
        turnoff();
        }
    }