#132. Formula: sum of the numbers from 1 to n (with a formula)
Find the sum of the numbers from 1 to n (with a formula). Formula: `n * (n + 1) // 2`
### Input
Each on its own line: n (1 ≤ value ≤ 10).
### Output
One integer.
Examples
Input
1
Output
1
Input
5
Output
15
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.