chinese_winter_solstice_onbefore
int s1 = chinese_winter_solstice_onbefore(rd);
int s2 = chinese_winter_solstice_onbefore(s1 + 370);
int s1 = chinese_winter_solstice_onbefore(rd);
int s2 = chinese_winter_solstice_onbefore(s1 + 370);