## Magic Tower

Statement

## Goal

You are a powerful magician-developer moving through a strange valley where towers magically appear.Each tower has a height, and you have the ability to create or destroy towers.

- Creating a tower cost the energy same as its height.

- Destroying a tower gives you the same energy as its height.

if A is positive, this means you create a tower of height A, which costs you A units of energy.

If A is negative, this means you destroy a tower of height |A|, which gives you |A| units of energy.

Your objective is to calculate the energy remaining after performing a series of actions on the towers.

Input

**Line 1:**An integer

`N`for the number of actions to perform.

**Next**An integer

`N`lines:`A`for an action.

Output

**Line 1:**An integer representing the energy remaining after all actions have been performed.

Constraints

1 ≤

-10^4 ≤

`N`≤ 10^4.-10^4 ≤

`A`≤ 10^4.Example

Input

5 4 -2 3 -1 2

Output

-6

Game modes

Fastest

Test cases

Test 1 Test

Input

5
4
-2
3
-1
2

Output

-6

Validator 1 Validator

Input

5
4
-2
3
-1
1

Output

-5

Test 2 Test

Input

3
5
-3
2

Output

-4

Validator 2 Validator

Input

3
5
-3
3

Output

-5

Test 3 Test

Input

4
6
-4
-2
1

Output

-1

Validator 3 Validator

Input

4
6
-4
-2
2

Output

-2

Test 4 Test

Input

2
10
-3

Output

-7

Validator 4 Validator

Input

2
9
-5

Output

-4

Solution language

Solution

Stub generator input