def dia_mes_proper1(ldies, dia):
    dia_proper = ldies[0]
    interval = abs(dia_proper - dia)
    for d in ldies[1:]:
        interval2 = abs(d - dia)
        if interval2 < interval:
            dia_proper = d
            interval = interval2
    return dia_proper, interval.days


def dia_mes_proper2(ldies, dia):
    dia_proper = min(ldies, key=lambda d: abs(d - dia))
    return dia_proper, abs(dia - dia_proper).days

# tria la solució que vulguis provar
dia_mes_proper = dia_mes_proper1