# """
# This is the interface that allows for creating nested lists.
# You should not implement it, or speculate about its implementation
# """
#class NestedInteger:
#    def isInteger(self) -> bool:
#        """
#        @return True if this NestedInteger holds a single integer, rather than a nested list.
#        """
#
#    def getInteger(self) -> int:
#        """
#        @return the single integer that this NestedInteger holds, if it holds a single integer
#        Return None if this NestedInteger holds a nested list
#        """
#
#    def getList(self) -> [NestedInteger]:
#        """
#        @return the nested list that this NestedInteger holds, if it holds a nested list
#        Return None if this NestedInteger holds a single integer
#        """

class NestedIterator:
    def __init__(self, nestedList: [NestedInteger]):
        #flatten in the constructor
        self.nums = []
        self._dfs(nestedList)
        self.pointer = 0
    
    def _dfs(self, nestedList):
        if not nestedList:
            return 
        for l in nestedList:
            if l.isInteger():
                self.nums.append(l.getInteger())
            else:
                self._dfs(l.getList())
    
    def next(self) -> int:
        if self.pointer >= len(self.nums):
            return -1
        ans = self.nums[self.pointer]
        self.pointer += 1
        return ans
    
    def hasNext(self) -> bool:
        return self.pointer < len(self.nums)
         

# Your NestedIterator object will be instantiated and called as such:
# i, v = NestedIterator(nestedList), []
# while i.hasNext(): v.append(i.next())