PROGRAMMING:Finding the cumulative sum of n
Using high precision method, find the exact value of S = 1 + 2 + 3 +... + n (n is input as a general integer).
###Input format:
a number
###Output format:
a number
###Input example:
```in
ten
```
###Output example:
```out
fifty-five
```
answer:If there is no answer, please comment
###Input format:
a number
###Output format:
a number
###Input example:
```in
ten
```
###Output example:
```out
fifty-five
```
answer:If there is no answer, please comment