function schoolRegister(input) {
    const register = {};

  for (let student of input) {
    student = student.split(', ');
    const currentStudent = student.shift().split(': ')[1];
    const currentGrade = Number(student.shift().split(': ')[1]) + 1;
    const currentScore = student.shift().split(': ')[1];

    if (currentScore > 3) {
        if (!register.hasOwnProperty(currentGrade)) {
            register[currentGrade] = {
                name: [currentStudent],
                score: [currentScore],
            };
        } else {
            register[currentGrade].name.push(currentStudent);
            register[currentGrade].score.push(currentScore);
        }
    }
  }
 const sortedGrades = sortRegister(register);

  for (const grade in sortedGrades) {
    console.log(`${grade} Grade`);
    console.log(`List of students: ${sortedGrades[grade].name.join(', ')}`);
    console.log(`Average annual score from last year: ${getAvarage(sortedGrades[grade].score).toFixed(2)}`);
    console.log('');
  }

  function sortRegister(obj) {
    Object.keys(obj).sort((a,b) => Number(a) - Number(b));
    return obj;
  }

  function getAvarage(arr) {
    let avrg = arr.map(x => Number(x)).reduce((acc, score) => acc + score ,0) / arr.length;
    return avrg;
  }
}