1
var numWaterBottles = function (numBottles, numExchange) {
2
  let count = 0;
3
  let emptyBottles = 0;
4
  while (numBottles > 0) {
5
    count += numBottles;
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    emptyBottles += numBottles;
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    numBottles = Math.floor(emptyBottles / numExchange);
8
    emptyBottles -= numBottles * numExchange;
9
  }
10

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  return count;
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};