PROGRAMMING:For loop exercise: 1 to x cumulative sum, and output in the specified format.

It is required to read in an integer x, and then output the sum of 1 + 2 + 3 +... X.
###Input format:
Positive integer x
###Output format:
1 +... + x = result
###Input example:
```in
four
```
###Output example:
```out
1+...+4=10
```







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