# The Cubes

You are given cubes of blue, yellow, and green colors. There are $a$, $b$, and $c$ cubes of each color respectively. All the cubes of each color are uniquely numbered with integers from $1$ to $a$, $b$, and $c$ (and thus, all the cubes are different from each other).

Let a set of cubes be interesting if it has at least two cubes, and all cubes in it have different colors.

Count the number of interesting sets you can construct using given cubes.

For example, if there is $1$ blue cube, $2$ yellow cubes, and $1$ green cube, there are $7$ interesting sets:

`first`

blue cube and`first`

yellow cube;`first`

blue cube and`second`

yellow cube;`first`

blue cube and`first`

green cube;`first`

yellow cube and`first`

green cube;`second`

yellow cube and`first`

green cube;`first`

blue cube,`first`

yellow cube and`first`

green cube;`first`

blue cube,`second`

yellow cube and`first`

green cube;

## Input

The first and only line contains three integers $a$, $b$, $c$ $(0≤a,b,c≤1000)$ — the number of cubes of each color.

## Output

The first and only line should contain the number of interesting sets of cubes.

## Examples

## Note

The first test was explained in the statement.

In the second test, there are only $2$ interesting sets of cubes:

`first`

yellow cube and`first`

green cube;`second`

yellow cube and`first`

green cube.

## Scoring

($14$ points): $a,b,c≤1$;

($8$ points): $b=0$; $c=0$;

($12$ points): $c=0$;

($16$ points): no additional constraints.