function check(f) {
	if (f.t1.value==""){	
		alert("\nキーワードを入力してください");
		f.t1.focus();
		return false;
 	}
		return true;

	      }

var iValue,rNumber;

var img1=new Image();
var img2=new Image();
var img3=new Image();
var img4=new Image();
var img5=new Image();
var img6=new Image();
var img7=new Image();
var img8=new Image();
var img9=new Image();
var img10=new Image();
var img11=new Image();
var img12=new Image();
var img13=new Image();
var img14=new Image();
var img15=new Image();
var img16=new Image();
var img17=new Image();
var img18=new Image();
var img19=new Image();
var img20=new Image();
img1.src="../../images/n/1.jpg";
img2.src="../../images/n/2.jpg";
img3.src="../../images/n/3.jpg";
img4.src="../../images/n/4.jpg";
img5.src="../../images/n/5.jpg";
img6.src="../../images/n/6.jpg";
img7.src="../../images/n/7.jpg";
img8.src="../../images/n/8.jpg";
img9.src="../../images/n/9.jpg";
img10.src="../../images/n/10.jpg";
img11.src="../../images/n/11.jpg";
img12.src="../../images/n/12.jpg";
img13.src="../../images/n/13.jpg";
img14.src="../../images/n/14.jpg";
img15.src="../../images/n/15.jpg";
img16.src="../../images/n/16.jpg";
img17.src="../../images/n/17.jpg";
img18.src="../../images/n/18.jpg";
img19.src="../../images/n/19.jpg";
img20.src="../../images/n/20.jpg";

function displayImage(){
	iValue=Math.random()*20;
	rNumber=Math.ceil(iValue);
	if(rNumber==0)rNumber++;
	document.image1.src=eval("img"+rNumber+".src")
}