function rangeRandom(num1,num2)	{
	if((num1 - num2) > 0)	{
		var big = num1
		var small = num2
	} else	{
		var big = num2
		var small = num1
	}
	var range = big - small + 1
	var number = Math.floor(Math.random()*range) + small
	return(number)
}

function randomImg()	{
	var img_src = "img/random_img/i_main" + rangeRandom(1,19) + ".jpg"
	document.write("<img id=\"main\" src='" + img_src + "'  alt=\"トップイメージ\"  width=\"682\" height=\"408\">")
}