//@version=6
strategy("Two/four crossover", overlay = true,
  initial_capital = 10000, pyramiding = 0,
  default_qty_type = strategy.fixed,
  default_qty_value = 1,
  commission_type = strategy.commission.cash_per_order,
  commission_value = 1, slippage = 1,
  margin_long = 100, margin_short = 100)
fastLength = input.int(2, "Fast", minval = 1)
slowLength = input.int(4, "Slow", minval = 2)
if fastLength >= slowLength or not timeframe.isdaily
    runtime.error("Use daily bars and fast < slow")
fast = ta.sma(close, fastLength)
slow = ta.sma(close, slowLength)
up = ta.crossover(fast, slow)
down = ta.crossunder(fast, slow)
if barstate.isconfirmed
    if up and strategy.position_size == 0
        strategy.entry("L", strategy.long)
    if down and strategy.position_size > 0
        strategy.close("L")
plot(fast, "Fast", color.blue)
plot(slow, "Slow", color.gray)