function IsUnsignedInteger(a){return/^d+$/.test(a)?1:0}function isLeapYear(a){return a%4==0&&a%100!=0||a%400==0?!0:!1}function cmpltDate(a){a=a.split("/");a[0].length==1&&(a[0]="0"+a[0]);a[1].length==1&&(a[1]="0"+a[1]);return a[0]+"/"+a[1]+"/"+a[2]}function getYomeiShana(a,c){var b;a==0||a==2||a==4||a==6||a==7||a==9||a==11?b=31:a==3||a==5||a==8||a==10?b=30:a==1&&(b=isLeapYear(c)?29:28);return b}
function returnNights(){var a=document.getElementById("hs_arrival").value,c=document.getElementById("s_nights"),c=c[c.selectedIndex].value,b=a.split("/"),a=eval(b[0]),d=eval(b[1]),b=eval(b[2]);a+=eval(c);a>getYomeiShana(d-1,b)&&(a-=getYomeiShana(d-1,b),d++,d>12&&(d-=12,b++));document.getElementById("hs_departure").value=cmpltDate(a+"/"+d+"/"+b)};