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var findSecondMinimumValue = function (root) {
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  let firstMin = Math.min();
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  let secondMin = Math.min();
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  const que = [root];
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  while (que.length) {
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    const node = que.shift();
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    if (node.val <= firstMin) {
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      if (node.val < firstMin) secondMin = firstMin;
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      firstMin = node.val;
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    } else if (node.val <= secondMin) {
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      secondMin = node.val;
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    }
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    if (node.left) que.push(node.left);
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    if (node.right) que.push(node.right);
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  }
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  return secondMin === Math.min() ? -1 : secondMin;
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};