# трассировка времени между датами
def dt_diff(dt1, dt2):
    if dt1>dt2:
        td = dt1 - dt2
        #~ dd = dt1.day - dt2.day
        mdt = dt2
        mdt_const = dt2
        edt = dt1
        future = True
    else:
        td = dt2 - dt1
        #~ dd = dt2.day - dt1.day
        mdt = dt1
        mdt_const = dt1
        edt = dt2
        future = False
    total_days = td.days
    years,months,days,hours,minutes,seconds=0,0,0,0,0,0
    for d in range(total_days):
        old_dt = mdt
        mdt = mdt + timedelta(days=1)
        #~ if mdt.year!=old_dt.year:
            #~ years += 1
            #~ months = 0
        #~ if mdt.month!=old_dt.month:
            #~ months += 1
            #~ days = 0
        if mdt.day!=old_dt.day:
            days += 1
        wd,md = calendar.monthrange(mdt.year, mdt.month)
        if (mdt_const.day==mdt.day):
            months += 1
            days = 0
        elif (mdt_const.day>md):
            if days>md-1:
                months += 1
                days = 0
        if months>11:
            years += 1
            months = 0
            #~ if days>365:
                #~ days=0
    time_td = edt - mdt
    hms = td_format_time(time_td)
    res = []
    if years>0:
        res.append(str(years) + mc(" год"," года"," лет",years))
    if months>0:
        res.append(str(months) + mc(" месяц"," месяца"," месяцев",months))
    if days>0:
        res.append(str(days) + mc(" день"," дня"," дней",days))
    if hms[0]>0:
        res.append(str(hms[0]) + mc(" час"," часа"," часов",hms[0]))
    if hms[1]>0:
        res.append(str(hms[1]) + mc(" минута"," минуты"," минут",hms[1]))
    if hms[2]>0:
        res.append(str(hms[2]) + mc(" секунда"," секунды"," секунд",hms[2]))
    return " ".join(res),future