Problem Statement

At the ranch run by Core-san, $N$ horses numbered $1, 2, \dots, N$ are raised.
Core-san decided to have these $N$ horses race according to the following rules.

• All horses start running simultaneously from a common starting point and race to a common finish point.
  The race course is a straight line, and the length from the starting point to the finish point is $1000$ meters.

When this race was held, the following held for $i = 1, 2, \dots, N-1$.

• When horse $i$ finished, horse $(i + 1)$ was running $A_{i}$ meters behind horse $i$.

When horse $1$ finished, how many meters behind horse $1$ was horse $N$ running?

Here, assume that each horse always runs at a constant speed.

Constraints

• $2 \leq N \leq 100$

• $0 \leq A_{i} \leq 10$ $(1 \leq i \leq N-1)$

• All inputs are integers.

Input

The input is given in the following format.

$N$
$A_{1}$ $A_{2}$ $\cdots$ $A_{N-1}$

• The $1$st line contains $N$.

• The $2$nd line contains $A_{1}, A_{2}, \dots, A_{N-1}$ in this order, separated by single spaces.

Output

Print the answer on $1$ line, followed by a newline.

The output is judged as correct if its absolute or relative error from the expected answer is at most $10^{−6}$.

Sample

3
10 10

19.9

11
1 2 3 4 5 6 7 8 9 10

53.6979931256464667570490112

8
0 0 0 0 0 0 0

0

2
10

10