I need help with deciding if L1 is context-free.

$$L_1 = \{a^pb^{q+r}c^sd^{q+t}e^{p+r} \mid p, q, r, s \ge 0\ , s > t\}$$

Can be rewritten into:


$$L_1 = \{a^pb^qb^rc^sd^qd^te^pe^r \mid p, q, r, s \ge 0\ , s > t\}$$

When we see the first occurence of c, we push the c:s onto the stack. But we can't make difference between d^q and d^t,  so comparing s < t is impossible when popping the d:s. 

Hence L1 is not Context-Free.


Is my reasoning right ?