// JavaScript Document
function setDate() {
year_month = document.getElementById('arr_month').value;
day = document.getElementById('arr_day').value;
year = year_month.charAt(0)+year_month.charAt(1)+year_month.charAt(2)+year_month.charAt(3);
month =  year_month.charAt(4)+year_month.charAt(5);

document.getElementById('start_date').value = year+"-"+month+"-"+day;

}