def transition(old, new, jugs):
    """
    returns a string explaining the transition from old state/node to new state/node
    
    old: a list representing old state/node
    new: a list representing new state/node
    jugs: a list of two integers representing volumes of the jugs
    """
    
    a = old[0]
    b = old[1]
    a_prime = new[0]
    b_prime = new[1]
    a_max = jugs[0]
    b_max = jugs[1]

    if a > a_prime:
        if b == b_prime:
            return "Clear {0}-liter jug:\t\t\t".format(a_max)
        else:
            return "Pour {0}-liter jug into {1}-liter jug:\t".format(a_max, b_max)
    else:
        if b > b_prime:
            if a == a_prime:
                return "Clear {0}-liter jug:\t\t\t".format(b_max)
            else:
                return "Pour {0}-liter jug into {1}-liter jug:\t".format(b_max, a_max)
        else:
            if a == a_prime:
                return "Fill {0}-liter jug:\t\t\t".format(b_max)
            else:
                return "Fill {0}-liter jug:\t\t\t".format(a_max)