PROGRAMMING:Finding the sum of the factorial of the first n terms

Input an integer n from the keyboard, find the sum of the factorial of the first n terms, 1 + 2+ 3!+...+ n! The sum of
###Input format:
Enter an integer greater than 1. For example, enter 20.
###Output format:
Output an integer. For example: 256132749411820313.
###Input example:
Here is a set of inputs. For example:
```in
twenty
```
###Output example:
The corresponding output is given here. For example:
```out
2561327494111820313
```







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