First line contains an integer $T$, which indicates the number of test cases.
Every test case begins with an integers $N$, which is the length of array $x$.
The second line contains $N-1$ integers $a_1$, $a_2$, $\cdots$, $a_{N-1}$, indicating the array $a$.
Limits
$1 \leq T \leq 50$.
$1 \leq N \leq 2000$.
$0 < a_i \leq 10^4$.
For 80\% of the use cases, $1 \leq N \leq 100$ holds.
Case #1: 5.77350
Case #2: 5.47723