Write a C++ program to check if a given string begins with 'abc' or 'xyz'. If the string begins with 'abc' or 'xyz' return 'abc' or 'xyz' otherwise return the empty string

#include <iostream>
using namespace std;

string test(string s1) 
        {
          if (s1.substr(0,3) == "abc")
            {
                return "abc";
            }
            else if (s1.substr(0,3) == "xyz")
            {
                return "xyz";
            }
            else
            {
                return "";
            }
        }
        
int main() 
 {
  cout << test("abc") << endl;  
  cout << test("abcdef") << endl; 
  cout << test("C") << endl;  
  cout << test("xyz") << endl;  
  cout << test("xyzsder") << endl;  
  return 0;    
}