Excellent Grades

In order to receive his propedeutic degree cum laude, the weighted average of all of Eddie's grades must be at least 8.0. Of course he must also have passed all of his courses, which requires a grade of at least 5.8. With only one exam to go, Eddie is wondering if he still has a shot at achieving cum laude.

Given all of the grades for Eddie's previous courses and their weights, and the weight of the final exam, check if Eddie can still obtain his degree cum laude. If he can, output the grade Eddie requires for his final exam to achieve this. Otherwise output IMPOSSIBLE.

• A line with 1 integer $w_u$ $(1 \leq w_u \leq 30)$, the weight of the final exam
• A line with 1 integer $n$ $(1 \leq n \leq 100)$, the number of other grades
• $n$ lines with 1 double (1 decimal) $g_i$ $(1 \leq g_i \leq 10)$ and 1 integer $w_i$ $(1\leq w_i \leq 30)$ where $g$ is the grade of exam $i$ and $w_i$ is the weight of exam $i$.

If Eddie can achieve cum laude, print the grade $g$ $(1 \leq g \leq 10)$ he has to achieve on his final exam, rounded to 1 decimal. Otherwise print IMPOSSIBLE.