r_img = new Array();
r_url = new Array();
r_window = new Array();

r_img [0] ='/i/banner/banner_tyubo.jpg';
r_url [0] ='/resource/landfill/index.html';
r_window [0] ='';

r_img [1] ='/i/banner/banner_ogasawara.jpg';
r_url [1] ='/nature/island/ogasawara/index.html';
r_window [1] ='';

r_img [2] ='/i/banner/banner_asbest.jpg';
r_url [2] ='/air/air_pollution/asbestos/index.html';
r_window [2] ='';

r_img [3] ='/i/banner/banner_ev.jpg';
r_url [3] ='/vehicle/sgw/promotion/index.html';
r_window [3] ='';

r_img [4] ='/i/banner/banner_diesel.jpg';
r_url [4] ='/vehicle/air_pollution/diesel/index.html';
r_window [4] ='';

n = Math.floor(Math.random()*r_img.length);
m = Math.floor(Math.random()*r_img.length);

while (n == m){
    m = Math.floor(Math.random()*r_img.length);
}

document.write("<li><a href='"+r_url[n]+"'"+r_window[n]+"><img src='"+r_img[n]+"' alt='' width='190' height='50' /></a></li>");
document.write("<li><a href='"+r_url[m]+"'"+r_window[m]+"><img src='"+r_img[m]+"' alt='' width='190' height='50' /></a></li>");