PROGRAMMING:Smart Gauss
When Gauss, a famous German mathematician, was in primary school, his teacher asked us to calculate:
$$1 + 2 + 3 + 4 + \cdots + 100 = \ ?$$
Gauss was the first to figure out the answer while everyone was still busy adding. Do you know what he does?
Please write a program, input positive integer $$n $$, calculate $$s = 1 + 2 + 3 + 4 + \ cdots + n $$, and output the value of $$s $.
####Input format
> $$n$$
####Output format
> $$s$$
####Input sample
```in
one hundred
```
####Output sample
```out
five thousand and fifty
```
answer：If there is no answer, please comment
In this paper, the sum formula of arithmetic sequence should be used instead of circular statement.
$$1 + 2 + 3 + 4 + \cdots + 100 = \ ?$$
Gauss was the first to figure out the answer while everyone was still busy adding. Do you know what he does?
Please write a program, input positive integer $$n $$, calculate $$s = 1 + 2 + 3 + 4 + \ cdots + n $$, and output the value of $$s $.
####Input format
> $$n$$
####Output format
> $$s$$
####Input sample
```in
one hundred
```
####Output sample
```out
five thousand and fifty
```
answer：If there is no answer, please comment
In this paper, the sum formula of arithmetic sequence should be used instead of circular statement.