Based on the news about the stock in the past five trading days, please predict the rise or fall of the stock in the next trading day. If the stock is predicted to rise in the next trading day, please output [Rise], if the stock is predicted to fall in the next trading day, please output [Decrease].

Date:2018-09-21, Stock:RIO, The news for the past five days is as follows:
2018-09-14: NEWS1: [$$] Norway's Norsk Hydro Pulls $345M Acquisition of Rio Tinto Assets.
2018-09-17: NEWS1: Asian Markets Mostly Lower As U.S.-China Trade Tensions Escalate.NEWS2: Asian Markets Mostly Lower As U.S.-China Trade Tensions Escalate.NEWS3: Australian Market Loses.NEWS4: Australian Market Loses.NEWS5: Top 4 Coal-Mining Stocks as of September 2018.
2018-09-18: NEWS1: Asian Markets Rise Despite Escalating Trade Tensions.NEWS2: Asian Markets Rise Despite Escalating Trade Tensions.NEWS3: Australian Market Rises.NEWS4: Australian Market Rises.NEWS5: [$$] BHP’s Andrew Mackenzie sees total pay climb to $4.65m.NEWS6: Asian Shares Mostly Higher As Investors Shrug Off New Tariffs.NEWS7: Asian Shares Mostly Higher As Investors Shrug Off New Tariffs.
2018-09-19: NEWS1: Rio Tinto Details $3.2 Bln Share Buy-back.NEWS2: Rio Tinto Details $3.2 Bln Share Buy-back.NEWS3: European markets open higher, brushing off trade dispute.
2018-09-20: NEWS1: Energy Sector Update for 09/20/2018: LGCY,NOA,NOA.TO,RIO,RRC.NEWS2: Energy Sector Update for 09/20/2018: LGCY,NOA,NOA.TO,RIO,RRC.NEWS3: Energy Sector Update for 09/20/2018: NOA,NOA.TO,RIO,RRC.NEWS4: Energy Sector Update for 09/20/2018: NOA,NOA.TO,RIO,RRC.NEWS5: Energy Sector Update for 09/20/2018: USO, UNG, RIO.NEWS6: Energy Sector Update for 09/20/2018: USO, UNG, RIO.NEWS7: Pre-Market Most Active for Sep 20, 2018 :  CRON, MU, TLRY, GE, EUFN, QQQ, NIO, CGC, BABA, BOTZ, EQNR, RIO.NEWS8: Pre-Market Most Active for Sep 20, 2018 :  CRON, MU, TLRY, GE, EUFN, QQQ, NIO, CGC, BABA, BOTZ, EQNR, RIO.NEWS9: [$$] Rio Tinto details $3.2bn share buyback.NEWS10: Rio Tinto announces new $3.2 billion share buyback, stock rises.NEWS11: Rio Tinto announces new $3.2 billion share buyback, stock rises.NEWS12: European shares add to gains as trade war fears fade.NEWS13: [$$] Opening Quote: Kier determined not to be the next Carillion .NEWS14: [$$] Rio Tinto issues details on returning $3.2bn to shareholders.NEWS15: [$$] Rio Tinto Plans Buybacks to Return Cash to Shareholders.

Answer: Rise