function random_img1(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 random_img2() {
		var img_src = "images/mainvisual/mainvisual_" + random_img1(1,2) + ".jpg"
		document.write("<IMG SRC='"+ img_src + "'>")
}