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Score : $100$ points

### Problem Statement

There are $N$ children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give $1$ candy to the first child in the line, $2$ candies to the second child, ..., $N$ candies to the $N$-th child. How many candies will be necessary in total?

### Constraints

• $1≦N≦100$

### Input

The input is given from Standard Input in the following format:

$N$


### Output

Print the necessary number of candies in total.

### Sample Input 1

3


### Sample Output 1

6


The answer is $1+2+3=6$.

### Sample Input 2

10


### Sample Output 2

55


The sum of the integers from $1$ to $10$ is $55$.

### Sample Input 3

1


### Sample Output 3

1


Only one child. The answer is $1$ in this case.