iteration.barrett

var
    X, Y, Z, I;

begin
    X := 1;

    { Loop to print odd numbers between 1 and 99 }
    while (X < 100) do
    begin
        WriteLn(X);
        X := X + 2;
    end;
    WriteLn;


    { Iterative Fibonacci - up to 20th number}
    X := 0;
    Y := 1;
    Z := 1;

    I := 0;
    while (I < 20) do
    begin
        X := Y;
        Y := Z;
        Z := X + Y;
        I := I + 1;
    end;
    WriteLn(X);
    WriteLn;


    { Nested loops }
    X := 0;
    while (X < 10) do
    begin
        Y := 0;
        while (Y < 10) do
        begin
            WriteLn(X, Y);
            Y := Y + 1;
        end;
        X := X + 1;
    end;


end;