Need help with quiz challenge

var quiz = [
  ["How presidents have there been?",44],
  ["How many states are there?",50],
  ["How many stripes are on the American Flag?",13]
];
var correctQuestions = [
];
var incorrectQuestions = [
];
var correctAnswers = 0;
var question;
var answer;
var response;
var html;
function print(message) {
  var outputDIV = document.getElementById("output");
  outputDIV.innerHTML = message;
}

function buildList(arr) {
  var listHTML = "<ol>";
  for (var i = 0;  i < arr.length; i += 1) {
    listHTML += "<li>" + arr[i] + "</li>"
  }
  listHTML = "</ol>";
  return listHTML;  
}

for (var i = 0; i < quiz.length; i += 1) {
  question = quiz[i][0];
  answer = quiz[i][1];
  response = prompt(question);
  response = parseInt(response);
  if (response === answer) {
    correctAnswers += 1;
    correctQuestions.push(question);
  } else {
    incorrectQuestions.push(question);
  }
}
html = "You got " + correctAnswers + " question(s) right.";
html += "<h2>You got these questions correct:</h2>";
html += buildList(correctQuestions);
html += "<h2>You got these questions wrong:</h2>"
html += buildList(incorrectQuestions);
print(html);