#include <iostream>
#include <string>

using namespace std;

string CleanString(string word){
   size_t i;
   string rv;

   for(i =0; i < word.size(); ++i) {
       if (isalpha(word[i])) {
          rv = rv + static_cast<char>(tolower(word[i]));
       }
   }
   return rv;
}