strategy("4 Semanas opening, 4 closing_Close")
a = max(close[1],max(close[2],max(close[3],max(close[4],max(close[5],max(close[6],max(close[7],max(close[8],max(close[9],max(close[10],max(close[11],max(close[12],max(close[13],max(close[14],max(close[15],max(close[16],max(close[17],max(close[18],max(close[19],close[20])))))))))))))))))))
b = min(close[1],min(close[2],min(close[3],min(close[4],min(close[5],min(close[6],min(close[7],min(close[8],min(close[9],min(close[10],min(close[11],min(close[12],min(close[13],min(close[14],min(close[15],min(close[16],min(close[17],min(close[18],min(close[19],close[20])))))))))))))))))))

longCondition = close > a
shortCondition = close < b   

strategy.entry ("long", strategy.long, when = longCondition)
strategy.entry ("short", strategy.short, when = shortCondition)
strategy.close ("long", when=shortCondition)
strategy.close ("short", when=longCondition)