Display blog posts in two columns

[saladgg]

I want to diplay the list of my blog posts in a row with two columns. So I tried;

{% for post in posts %}
    {% set oddOrEven = cycle(['odd', 'even'], loop.index0) %}
    {% if oddOrEven == 'odd' %}
        <div class="col-md-6">Odd posts</div>
    {% else %}
        <div class="col-md-6">Even posts</div>
    {% endif %}
{% endfor %}

But I get the error:

Invalid block tag on line 18: 'set', expected 'empty' or 'endfor'. Did you forget to register or load this tag?

#18: {% set oddOrEven = cycle(['odd', 'even'], loop.index0) %}

What am I missing or what is the right approach?