function getLastMonthDate(){
	var date = new Date();
	date.setMonth(date.getMonth()-1);

	return "(" + date.getFullYear() + ". " + (date.getMonth()+1) + ". " + getLastDays(date.getFullYear(), date.getMonth()+1) + " ÇöÀç)";
}

function getLastDays(year, month){
	var lastdays = new Array(12);
	lastdays[1]  = 31;
	lastdays[2]  = 0;
	lastdays[3]  = 31;
	lastdays[4]  = 30;
	lastdays[5]  = 31;
	lastdays[6]  = 30;
	lastdays[7]  = 31;
	lastdays[8]  = 31;
	lastdays[9]  = 30;
	lastdays[10] = 31;
	lastdays[11] = 30;
	lastdays[12] = 31;

	total_days = lastdays[month];
	if (total_days == 0) {
		// À±³â Á¶»ç
		if(((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))
			total_days = 29;
		else
		total_days = 28;
	}

	return total_days;
}

document.write(getLastMonthDate());