Lab1Challenge2Delphi

Uses
    System.SysUtils;

Var
    Index, I: Integer;
    IsCorrect: Boolean;
    Numbers: Array[0..1] of Integer;

Begin
    Index := 0;
    IsCorrect := False;
    Numbers[0] := 1; Numbers[1] := 1;

    Repeat
        Try
            Write('Index of Fibanacci array element (cannot be lower than 3): ');
            Readln(Index);
            If (Index >= 3) Then
            Begin
                IsCorrect := True;
            End
            Else
            Begin
                Writeln('Number must be not lower than 3!');
            End;
        Except
            Writeln('Enter number, not string or anything else!');
        End;
    Until IsCorrect;

    For i := 1 to (Index - 2) do
    Begin
        if (Numbers[0] < Numbers[1]) Then
        Begin
            Numbers[0] := Numbers[0] + Numbers[1];
        End
        Else
        Begin
            Numbers[1] := Numbers[1] + Numbers[0];
        End;
    End;

    Write(IntToStr(index) + ' item from array equals ');
    If (numbers[0] > numbers[1]) Then
    Begin
        Writeln(numbers[0]);
    End
    Else
    Begin
        Writeln(numbers[1]);
    End;

    Writeln('Press [ENTER] to close program...');
    Readln;
End.