GreeterV5-2.sol

pragma solidity ^0.4.18;

contract GreeterV5 {
    struct Greeting {
        string hello;
        string goodbye;
    }
    
    mapping (string => Greeting) countryToGreeting;

    function GreeterV3() public {
        countryToGreeting[""] = Greeting("Hello","Goodbye");    
    }
    
    function sayHello(string country) external view returns (string) {
        return countryToGreeting[country].hello;
    }
    
    function changeHello(string country,string hello) external {
        countryToGreeting[country].hello = hello;
    }
    
    function sayGoodbye(string country) external view returns (string) {
        return countryToGreeting[country].goodbye;
    }
    
    function changeGoodbye(string country,string goodbye) external {
        countryToGreeting[country].goodbye = goodbye;
    }

}