gets
arr = gets.chomp.split.map(&:to_i)

dp = {}
dp[0] = {}
dp[0][0] = arr[0]

dp[1] = {}
dp[1][0] = dp[0][0] + arr[1]
dp[1][1] = dp[0][0] - arr[1]
dp[1][2] = dp[0][0] * arr[1]
dp[1][3] = dp[0][0] / arr[1]

2.upto(arr.length - 1) do |i|
  dp[i] = {}
  c = 0
  0.upto(dp[i - 1].length- 1) do |j|
    dp[i][c] = dp[i - 1][j] + arr[i]
    c += 1
    dp[i][c] = dp[i - 1][j] - arr[i]
    c += 1
    dp[i][c] = dp[i - 1][j] * arr[i]
    c += 1
    dp[i][c] = dp[i - 1][j] / arr[i]
    c += 1
  end
end

max = -0xFFFFFFFFF
dp[arr.length - 1].map { |k| max = k[1] if max < k[1] }
puts max