PROGRAMMING:Gold coin
###Task description
The king paid gold coins as wages to loyal knights. On the first day, the knight received a gold coin; For the next two days (the second and the third), two gold coins were received each day; In the next three days (the fourth, fifth and sixth days), three gold coins were received every day; In the next four days (the seventh, eighth, ninth and tenth days), the knight will receive four gold coins every day. This mode of salary payment will continue like this: when he receives n gold coins every day for N consecutive days, the knight will receive n + 1 gold coins every day for N + 1 consecutive days (n is any positive integer).
You need to write a program to determine how many gold coins the knight has won in a given number of days from the first day.
###Input format:
An integer (range 1 to 10000) representing the number of days.
###Output format:
The number of gold coins the knight received.
###Input example:
```in
six
```
###Output example:
```out
fourteen
```
answer：If there is no answer, please comment
The king paid gold coins as wages to loyal knights. On the first day, the knight received a gold coin; For the next two days (the second and the third), two gold coins were received each day; In the next three days (the fourth, fifth and sixth days), three gold coins were received every day; In the next four days (the seventh, eighth, ninth and tenth days), the knight will receive four gold coins every day. This mode of salary payment will continue like this: when he receives n gold coins every day for N consecutive days, the knight will receive n + 1 gold coins every day for N + 1 consecutive days (n is any positive integer).
You need to write a program to determine how many gold coins the knight has won in a given number of days from the first day.
###Input format:
An integer (range 1 to 10000) representing the number of days.
###Output format:
The number of gold coins the knight received.
###Input example:
```in
six
```
###Output example:
```out
fourteen
```
answer：If there is no answer, please comment