i cannot be resolved to a variable

package com.imooc.method;

public class FacDemo {

//方法不能嵌套定义

//求阶乘的方法

public int fac(int n) {

int s=1;

for(int i=1;i<=n;i++) {

s=i*s;

}

return s;

}

public static void main(String[] args) {

FacDemo facDemo=new FacDemo();

int fac=facDemo.fac(3);

System.out.println("3!="+fac);

//求1!+2!+3!+4!+5!

for(int i=1;i<=5;i++);

fac=facDemo.fac(i);

sum

为什么会报错啊