Skip Negatives Before Summing

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Compute the sum of only nonnegative entries ($a_i\ge0$) among $n$ integers. Zero is valid. Print 0 for an empty sequence or when all entries are negative.

Input

First $n$ ($0\le n\le100000$), followed by exactly $n$ integers in $[-10^6,10^6]$.

Output

Print the sum as a signed 64-bit integer.

Subtasks

• Subtask 1 (20%): $0\le n\le 8$; $-10^6\le a_i\le10^6$.

• Subtask 2 (30%): $0\le n\le 1000$; $-10^6\le a_i\le10^6$.

• Subtask 3 (50%): $0\le n\le 100000$; $-10^6\le a_i\le10^6$.

Examples

Example 1

Input:

4
-3 0 8 -2

Output:

8

Explanation:

Keep nonnegative values [0, 8]; their sum is 8.

Example 2

Input:

3
-4 -2 -1

Output:

0

Explanation:

Keep nonnegative values []; their sum is 0.