C:\Users\86131\Desktop\c++\练习.cpp(23) : error C2143: syntax error : missing ';' before 'return'

#include<iostream>
using namespace std;
class Box
{
public:
    Box();
    Box(int w,int h,int l);
    Box(const Box &other);
    int V();
    int CV(Box other);
private:
    int width;
    int longth;
    int hight;
};
Box::Box():width(1),longth(1),hight(1){};
Box::Box(int l,int w,int h){width=w;longth=l;hight=h;}
Box::Box(const Box &other){width=other.width;longth=other.longth;hight=other.hight;}
int Box::V(){return width*longth*hight;}
int Box::CV(Box other){
    if(this->V()>other.V())return 1;
    else if(this->V()==other.V())return 0;
    else (this->V()<other.V())return -1;
}
int main(){
    Box s1;
    Box s2(2,8,6),s3(6,3,8);
    cout<<"s1体积为:"<<s1.V<<endl<<"s2体积为:"<<s2.V<<endl<<"s3体积为:"<<s3.V<<endl;
    if(s2.CV(s3)>0)cout<<"s2体积大于s3"<<endl;
    if(s2.CV(s3)==0)cout<<"s2体积等于s3"<<endl;
    if(s2.CV(s3)<0)cout<<"s2体积小于s3"<<endl;
    return 0;
}

运行结果及报错内容

C:\Users\86131\Desktop\c++\练习.cpp(23) : error C2143: syntax error : missing ';' before 'return'

我的解答思路和尝试过的方法

我想要达到的结果

我现在在计算体积和比较体积，但是提示我缺；但我没发现哪里缺；

23行，else后面加个if

else (this->V()<other.V())return -1;改成else return -1;或者else if(this->V()<other.V())return -1;
else后面不能有限制条件语句