How do I go about generating specific random letter generator? [duplicate]

This question already has an answer here:

• C++ random number from a set 5 answers

I want to generate a random letter generator with 4 specific letters. I know how to generate random letters between two letters for example L-P.

      #include <iostream>
      #include <string>
      #include <time.h>  
      using namespace std;

       int main()
    {


      for (int i = 0; i < 10; i++) 
      {
          char r = rand() % 5 + 'L';
          cout << r << endl;
      }



    }       

What I want to do however is generate 4 specific Letters at random for example, it generates one of the following letters. U , D , L , R.