let students = []; //this will be a two dimensional array of all the students' scores

//I'll assume the inputs come in as arrays of 2 numbers
let input = PAIR; //PAIR is the raw data being sent to the program
while(input[0] !== -1 && input[1] !== -1) {
    students.push(input);
    input = PAIR; //get new PAIR from input stream
}

let numberOfStudents = students.length;
console.log("N: " + numberOfStudents); //first output line (example, N: 4)

//average the numbers in the given array
let average = function(inArray) {
    let total = 0;

    for(let number of inArray) {
        total += number;
    }
    return (total / inArray.length);
}

let studentAverages = []; //1d array for the students averages
let currentStudent = 1; //for output purposes
for(let student of students) {
    studentAverages.push(average(student));

    //output line(s) (example, student 1: 93.5)
    console.log("student " + currentStudent + ":" + average(student));
}

let classAverage = average(studentAverages); //take the average of the student averages

//output line (example, class average: 74.875)
console.log("class average: " + classAverage);

let aboveAvg = 0;
let belowAvg = 0;
for(let average of studentAverages) { //for each student average

    if(average >= classAverage + 10) {
        aboveAvg += 1;

    } else if(average <= classAverage - 10) {
        belowAvg += 1;
    }
}

//output line (example, # of students 10 points or more above class average: 2)
console.log("# of students 10 points or more above class average: " + aboveAvg);

//last output line (example, # of students 10 points or more below class average: 1)
console.log("# of students 10 points or more below class average: " + belowAvg);