Decide if this language is context free I got this question for homework:

Decide if this language is context free or not:
$\qquad \{x@1^m: x \in \left\{0,1\right\}^*, m \in \mathbb{N}, x_m = 1\}$.

Intuitively I think it's not context-free because a $PDA$ can't remember the places of all the $1$'s in $x$.
I tried using the pumping lemma but couldn't find the right example to show the language is not context-free.
I'd be grateful for any lead.
Hint: Following up on Hendrik Jan's hint, here is another way to view this language:
$$
\{ x1y@1z : x,y \in \{0,1\}^*, z \in \{1\}^*, |x| = |z| \}.
$$