function schoolGrades(params) {
    let students = new Map();

    for (let string of params) {
        let tokens = string.split(' ');
        let name =  tokens[0];
        let grades = tokens.splice(1, tokens.length).map(Number);
        if (!students.has(name)) {
            students.set(name, []);
            students.get(name).push(...grades);
        }else{
            students.get(name).push(...grades);
        }
    }


    let sorted = [...students].sort((a, b) => average(a, b));

    for (let [name,grades] of sorted) {
        console.log(`${name}: ${grades.join(', ')}`);
    }

    function average (a, b){
        let aSum = 0;
        for (let i = 0; i < a[1].length; i++) {
            aSum +=a[1][i];

        }
        let bSum = 0;
        for (let i = 0; i < b[1].length; i++) {
            bSum += b[1][i];

        }
        let aAverage = aSum / a[1].length;
        let bAverage = bSum / b[1].length;
        return aAverage - bAverage;
    }
}