var numWaterBottles = function(numBottles, numExchange) {
    let drinked = 0;
    let empty = 0;
    while (numBottles + empty >= numExchange) {
        drinked += numBottles; 
        empty += numBottles;
        numBottles = Math.floor(empty / numExchange);
        empty -= numBottles * numExchange;
    }
    return drinked + numBottles;
};