Roof Us started in 2015 an investment project and had, in year 2017, inventories of $439,371 exclusively for the project, while the accounts payable ascended to $247,716 and the accounts receivable summed to $40,223. One year later, the inventories were $363,715, the accounts receivable were $46,375 and the accounts payable were $226,686. 

Calculate the cashflow due to changes in net working capital for year 2018. Remember that the sign for an increase in NWC will be negative.