function getGrade(data) {
function getGrade(data) {
    let nameMap = new Map()

    for (const array of data) {
        let name = array[0]
        let grade = Number(array[1])
        let subject = array[2]
        if (!nameMap.has(name)) {
            nameMap.set(name, new Map())
        }
        nameMap.get(name).set(subject, grade)
    }
    for (let [name, inerrMap] of nameMap) {
        for (const [subject, grade] of inerrMap) {
            console.log(`${name} -> ${subject}: ${grade}`)
        }
    }
}

let input = [
["Pesho", "5.80", "JS"],
["Vasil", "5.80", "JS"],
["Nikolai", "5.80", "JS"]]

getGrade(input)