/*--------------------------------------------------
created by smtuttle at Tue Oct 18 13:48:39 PDT 2016
--------------------------------------------------*/
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
using namespace std;


/*--------------------------------------------------
 signature: next_sound : string -> string
 purpose: expects an animal sound,
    "moo", "baa", "la la la", or "oink",
    and returns the "next" animal sound I should hear
    based on the the beginning of
    Sandra Boynton's "Moo, Baa, La La La":
    *   "moo"? -> "baa"
    *   "baa"? -> "la la la"
    *   "la la la"? -> "oink"
    *   "oink"? -> "moo"
    (if a non-animal sound is given, return "???")

 examples: next_sound("moo") == "baa"
           next_sound("baa") == "la la la"
           next_sound("la la la") == "oink"
           next_sound("oink") == "moo"
           next_sound("arf") == "???"
--------------------------------------------------*/

string next_sound(string an_animal_sound)
{
    if (an_animal_sound == "moo")
    {
        return "baa";
    }
    else if (an_animal_sound == "baa")
    {
        return "la la la";
    }
    else if (an_animal_sound == "la la la")
    {
        return "oink";
    }
    else if (an_animal_sound == "oink")
    {
        return "moo";
    }
    else
    {
        return "???";
    }
}