CDO

I am having trouble averaging the data by every two time steps. For example, if the data is like the following...

0,1,2,3,4,5, ...

I would like to average the data every two time steps like

(0+1)/2, (1+2)/2. (2+3)/2, (3+4)/2, (4+5)/2, ...

which overlaps the time steps for each averaging time step

For this, I am using timeselmean operator like the following

cdo --timestat_date first timeselmean,2,0,0 in.nc out.nc

which just gives me a result of

(0+1)/2, (2+3)/2. (4+5)/2, (6+7)/2, (8+9)/2, ...

How do I fix this?

Thanks.