def _interpolation_max_weighted_deg(n, tau, s):
    """Return the maximal weighted degree allowed for an interpolation
    polynomial over `n` points, correcting `tau` errors and with multiplicity
    `s`

    EXAMPLES::

        sage: from sage.coding.guruswami_sudan.interpolation import _interpolation_max_weighted_deg
        sage: _interpolation_max_weighted_deg(10, 3, 5)
        35
    """
    return (n-tau) * s