How to allocate multiple node types in SLURM job

Question

I want to allocate 'x' nodes of Node type A and 'y' nodes of Node type 'B' for a single SLURM job. How do we do it using Salloc command?

For single task we do like this

salloc -N 1 -C <nodetype1> --ntasks-per-node=1 --exclusive srun <..>

but for allocating multiple nodes I tried this

 1. salloc -N 1 -C <nodetype1> --ntasks-per-node=1 -N 2 -C <nodetype2> --ntasks-per-node=1 --exclusive srun <..>
 2. salloc -N 2 -C <nodetype1> --ntasks-per-node=1 -C <nodetype2> --ntasks-per-node=1 --exclusive srun <..>

These doesn't work