function randIdx(num){
	if(num<=0)return;
	var arrIdx = new Array();
	for(cnt=0;cnt<num;cnt++){
		var idx=Math.floor(Math.random()*arrRefUrl.length);
		var dupliFlg=chkDupli(arrIdx,idx);
		if(dupliFlg==false){
			arrIdx.push(idx);
		}
	}
	return arrIdx;
}

function chkDupli(arry,idx){
	var dupliFlg=false;
	for(cnt=0;cnt<arry.length;cnt++){
		if(arry[cnt]==idx){
			dupliFlg=true;
			break;
		}
	}
	return dupliFlg;
}

function createRefUrl(num){
	var arrIdx=randIdx(num);
	var strWrite="";
	for(cnt=0;cnt<arrIdx.length;cnt++){
		strWrite+="<a href='"+arrRefUrl[arrIdx[cnt]].url+"' target='_blank'>"+arrRefUrl[arrIdx[cnt]].title+"</a><br/>";
	}
	document.write(strWrite);
}