How can I calculate the cumulative simulation time in an old version Lammps?

Dear everyone,
I am trying to run my simulation on a computer cluster and the Lammps version is 11 Mar 2013. Although it is an old version, I do not have the permission to update it.
In current Lammps package, I can define a variable like variable mytime equal “time”, and then I can output the simulation time through the variable ‘mytime’. And in the old version, if I use fix dt/reset command, I can use f_fixID[1] to output cumulative simulation time.
But in some cases, fix dt/reset will not be used. My question is how I can calculate the cumulative simulation time and output it in the older version Lammps (version 11 Mar 2013) which does not support the thermo key word time?
Thanks very much for your help!


With My Best Regards