function pages(){
var aff = Math.ceil(18*Math.random());
if (aff==1) {window.open('prob/1.htm');}
if (aff==2) {window.open('prob/2.htm');}
if (aff==3) {window.open('prob/3.htm');}
if (aff==4) {window.open('prob/4.htm');}
if (aff==5) {window.open('prob/5.htm');}
if (aff==6) {window.open('prob/6.htm');}
if (aff==7) {window.open('prob/7.htm');}
if (aff==8) {window.open('prob/8.htm');}
if (aff==9) {window.open('prob/9.htm');}
if (aff==10) {window.open('prob/10.htm');}
if (aff==11) {window.open('prob/11.htm');}
if (aff==12) {window.open('prob/12.htm');}
if (aff==13) {window.open('prob/13.htm');}
if (aff==14) {window.open('prob/14.htm');}
if (aff==15) {window.open('prob/15.htm');}
if (aff==16) {window.open('prob/16.htm');}
if (aff==17) {window.open('prob/17.htm');}
if (aff==18) {window.open('prob/18.htm');}
}