#include <iostream>
#include <string>

using namespace std;

int main() {
     //string phrase {"this, is, a, list, of, words"};
     string phrase {""};

     // this, is, a, list, of, words
     // is, a, list, of, words
     // a, list, of, words
     // list, of, words
     // of, words
     // words
     //
     // the ouptut should be
     //   this
     //   is
     //   a
     //   list
     //   of
     //   words
     //
     size_t pos;

     pos = phrase.find(", ");
     while (pos != string::npos) {
        cout << phrase.substr(0,pos) << endl; phrase = phrase.substr(pos+2);
        pos = phrase.find(", ");
     }

     if (phrase.size() > 0) {
          cout << phrase << endl;
     }
     
     return 0;
}