Everything works, except document.write

function print(message) {
  document.write(message);
}

var questionS = [
  ['How many states does North America have?', '50'],
  ['Does a lion walk on 2 or 4 legs?', '4'],
  ['Is California located in the East Coast, or the West Coast of North America?','West Coast']
];

var correctAnswers = 0;
var wrongAnswers = 0;

function printQuestions(questions) {
  var listHTML = '<ol>';
  for ( var i = 0; i <= questionS.length; i += 1 ) {
    var question = prompt(questionS[i][0]);
    if ( question === questionS[i][1] ) {
      correctAnswers += 1;
      listHTML += '<li>' + questionS[i][1] + '</li>';
    } else {
      wrongAnswers += 1;
    }
  }
  listHTML += '</ol>';
}

printQuestions(questionS);

document.write('You got ' + correctAnswers + ' correct!');
document.write('You got ' + wrongAnswers + ' incorrect.');