Sum Range

Given an integer N, find the sum of all the numbers from 1 to N inclusive

Example 1

Input

1

Output

1
Explanation

The sum of all numbers from 1 to 1 = 1

Example 2

Input

5

Output

15
Explanation

The sum of all the numbers from 1 to 5 =
1 + 2 + 3 + 4 + 5 = 15

Example 3

Input

3

Output

6
Explanation

The sum of all the numbers from 1 to 3 =
1 + 2 + 3 = 6

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