PROGRAMMING:Calculating s=1+(1+2)+(1+2+3)+... ...+(1+2+...+n)

Given 1 integers `n`, you are supposed to output the value of 1+(1+2)+(1+2+3)+... ...+(1+2+...+n).
### Input Specification:
Each input file contains one test case, which gives `n` in a line.
### Output Specification:
For each test case, print in a line the value of `1+(1+2)+(1+2+3)+... ...+(1+2+...+n)` by `s=value`
### Sample Input:
```in
three
```
### Sample Output:
Write the corresponding sample output here. For example:
```out
s=10
```







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