Summing Consecutive Integers

Source: beecrowd

Version: Phuoc Hung OJ Extended

Problem Statement

Read integer $A$, then keep reading candidate values for $N$ until the first strictly positive value. Ignore zero and negative candidates. Print the sum of exactly $N$ consecutive integers beginning at $A$ inclusive.

Input

One line contains $A$ followed by 1 to 100 candidate values for $N$; the final candidate is the first positive one. PHOJ bounds: $-1000\le A\le1000$, candidates in $[-1000,1000]$, accepted $N$ in $[1,1000]$.

Output

Print one integer, the requested sum.

Subtasks

• Subtask 1 (20%): At most 3 nonpositive candidates before the first positive $N$; $1\le N\le1000$.

• Subtask 2 (30%): At most 15 nonpositive candidates before the first positive $N$; $1\le N\le1000$.

• Subtask 3 (50%): At most 100 nonpositive candidates before the first positive $N$; $1\le N\le1000$.

Examples

Example 1

Input:

3 -2 0 2

Output:

7

Explanation:

Ignore nonpositive N candidates, then add exactly N integers starting from A.

Example 2

Input:

-3 0 -1 4

Output:

-6

Explanation:

Ignore nonpositive N candidates, then add exactly N integers starting from A.