def ltrmin(perm):
    """Returns the positions of the left-to-right minima.

    >>> Permutation(35412).ltrmin()
    [0, 3]
    """
    n = perm.__len__()
    L = []
    minval = len(perm) + 1
    for idx, val in enumerate(perm):
        if val < minval:
            L.append(idx)
            minval = val
    return L
