let e11 =
        let input = ... //Läser in input
        let parsed =
            input.Split [|'\n'|]
            |> Array.map (fun row -> List.ofArray (Array.map int (row.Split [|' '|])))
            |> List.ofArray

        let size = 4
        let outOfBoundsRight = List.length parsed - size
        let outOfBoundsLeft = size - 1
        let outOfBoundsDown = outOfBoundsRight

        let row (i:int) (j:int) (matrix: int list list) : int list =
            if j > outOfBoundsRight then [0]
            else [for a in 0 .. size - 1 -> matrix.[i].[j+a]]

        let col (i:int) (j:int) (matrix: int list list) : int list =
            if i > outOfBoundsDown then [0]
            else [for a in 0 .. size - 1 -> matrix.[i+a].[j]]

        let leftDia (i:int) (j:int) (matrix: int list list) : int list =
            if j < outOfBoundsLeft || i > outOfBoundsDown then [0]
            else [for a in 0 .. size - 1 -> matrix.[i+a].[j-a]]

        let rightDia (i:int) (j:int) (matrix: int list list) : int list =
            if i > outOfBoundsDown || j > outOfBoundsRight then [0]
            else [for a in 0 .. size - 1 -> matrix.[i+a].[j+a]]

        let product list =
            List.fold ( * ) 1 list

        List.init 20 (fun i ->
            List.init 20 (fun j ->
                [row i j parsed; col i j parsed; leftDia i j parsed; rightDia i j parsed]
                |> List.map (fun l -> product l)
                |> List.max))
        |> List.concat
        |> List.max