Finding the first element of a multi-indexed parameter

I have a multi-indexed parameter, say pMatrix(i,j). I want to efficiently get the first element of the matrix.

Applying the First-operator (i.e. First((i,j) | pMatrix(i,j))) did not work; it results in the following error: “The iterative operator first can have only one iterative index.”

I can think of some workarounds (such as to start by finding the first i, and given this i finding the first j), but this is quite cumbersome, especially when there are more than two indices (in our project we sometimes have up to 7 indices).

How should this be elegantly addressed?