
Extract the answer to the question from the following context.
Question: Which is not a last name, Nasser or Umm?
Context: Nasser's street following was still too small to sustain his plans for reform and to secure him in office. To promote himself and the Liberation Rally, he gave speeches in a cross-country tour, and imposed controls over the country's press by decreeing that all publications had to be approved by the party to prevent "sedition". Both Umm Kulthum and Abdel Halim Hafez, the leading Arab singers of the era, performed songs praising Nasser's nationalism. Others produced plays denigrating his political opponents. According to his associates, Nasser orchestrated the campaign himself. Arab nationalist terms such "Arab homeland" and "Arab nation" frequently began appearing in his speeches in 1954–55, whereas prior he would refer to the Arab "peoples" or the "Arab region". In January 1955, the RCC appointed him as their president, pending national elections.

Umm
