c++字符串连接

编写一个程序，将两个字符串连接起来，结果取代第一个字符串。要求用string方法。

int main(){
    	int a,b;
	cin >> a >> b;
	sort(a,b);
	cout << a << " "<< b;
	string s1,s2;
	cin >> s1 >> s2;
	string &s3 = s1; 
	s3=s1+s2;
	cout << s3 << " " << &s1 << " " << &s3 << "\n";
}