{"pre_text": ["( a ) the net change in the total valuation allowance for the years ended december 31 , 2018 and 2017 was an increase of $ 12 million and an increase of $ 26 million , respectively .", "deferred income tax assets and liabilities are recorded in the accompanying consolidated balance sheet under the captions deferred charges and other assets and deferred income taxes .", "there was a decrease in deferred income tax assets principally relating to the utilization of u.s .", "federal alternative minimum tax credits as permitted under tax reform .", "deferred tax liabilities increased primarily due to the tax deferral of the book gain recognized on the transfer of the north american consumer packaging business to a subsidiary of graphic packaging holding company .", "of the $ 1.5 billion of deferred tax liabilities for forestlands , related installment sales , and investment in subsidiary , $ 884 million is attributable to an investment in subsidiary and relates to a 2006 international paper installment sale of forestlands and $ 538 million is attributable to a 2007 temple-inland installment sale of forestlands ( see note 14 ) .", "a reconciliation of the beginning and ending amount of unrecognized tax benefits for the years ended december 31 , 2018 , 2017 and 2016 is as follows: ."], "post_text": ["if the company were to prevail on the unrecognized tax benefits recorded , substantially all of the balances at december 31 , 2018 , 2017 and 2016 would benefit the effective tax rate .", "the company accrues interest on unrecognized tax benefits as a component of interest expense .", "penalties , if incurred , are recognized as a component of income tax expense .", "the company had approximately $ 21 million and $ 17 million accrued for the payment of estimated interest and penalties associated with unrecognized tax benefits at december 31 , 2018 and 2017 , respectively .", "the major jurisdictions where the company files income tax returns are the united states , brazil , france , poland and russia .", "generally , tax years 2006 through 2017 remain open and subject to examination by the relevant tax authorities .", "the company frequently faces challenges regarding the amount of taxes due .", "these challenges include positions taken by the company related to the timing , nature , and amount of deductions and the allocation of income among various tax jurisdictions .", "pending audit settlements and the expiration of statute of limitations could reduce the uncertain tax positions by $ 30 million during the next twelve months .", "the brazilian federal revenue service has challenged the deductibility of goodwill amortization generated in a 2007 acquisition by international paper do brasil ltda. , a wholly-owned subsidiary of the company .", "the company received assessments for the tax years 2007-2015 totaling approximately $ 150 million in tax , and $ 380 million in interest and penalties as of december 31 , 2018 ( adjusted for variation in currency exchange rates ) .", "after a previous favorable ruling challenging the basis for these assessments , we received an unfavorable decision in october 2018 from the brazilian administrative council of tax appeals .", "the company intends to further appeal the matter in the brazilian federal courts in 2019 ; however , this tax litigation matter may take many years to resolve .", "the company believes that it has appropriately evaluated the transaction underlying these assessments , and has concluded based on brazilian tax law , that its tax position would be sustained .", "the company intends to vigorously defend its position against the current assessments and any similar assessments that may be issued for tax years subsequent to 2015 .", "international paper uses the flow-through method to account for investment tax credits earned on eligible open-loop biomass facilities and combined heat and power system expenditures .", "under this method , the investment tax credits are recognized as a reduction to income tax expense in the year they are earned rather than a reduction in the asset basis .", "the company recorded a tax benefit of $ 6 million during 2018 and recorded a tax benefit of $ 68 million during 2017 related to investment tax credits earned in tax years 2013-2017. ."], "table": [["in millions", "2018", "2017", "2016"], ["balance at january 1", "$ -188 ( 188 )", "$ -98 ( 98 )", "$ -150 ( 150 )"], ["( additions ) reductions based on tax positions related to current year", "-7 ( 7 )", "-54 ( 54 )", "-4 ( 4 )"], ["( additions ) for tax positions of prior years", "-37 ( 37 )", "-40 ( 40 )", "-3 ( 3 )"], ["reductions for tax positions of prior years", "5", "4", "33"], ["settlements", "2", "6", "19"], ["expiration of statutes oflimitations", "2", "1", "5"], ["currency translation adjustment", "3", "-7 ( 7 )", "2"], ["balance at december 31", "$ -220 ( 220 )", "$ -188 ( 188 )", "$ -98 ( 98 )"]], "table_ori": [["In millions", "2018", "2017", "2016"], ["Balance at January 1", "$(188)", "$(98)", "$(150)"], ["(Additions) reductions based on tax positions related to current year", "(7)", "(54)", "(4)"], ["(Additions) for tax positions of prior years", "(37)", "(40)", "(3)"], ["Reductions for tax positions of prior years", "5", "4", "33"], ["Settlements", "2", "6", "19"], ["Expiration of statutes oflimitations", "2", "1", "5"], ["Currency translation adjustment", "3", "(7)", "2"], ["Balance at December 31", "$(220)", "$(188)", "$(98)"]]}

Question: what is the highest value of reductions for tax positions of prior years?
Evidence:
table_4: in millions the reductions for tax positions of prior years of 2018 is 5 ; the reductions for tax positions of prior years of 2017 is 4 ; the reductions for tax positions of prior years of 2016 is 33 ;
Program: table_max(reductions for tax positions of prior years, none)
Answer:
str_answer: 33
exe_answer: 33