10731: ABC135 - A - Harmony
[Creator : ]
Description
We have two distinct integers $A$ and $B$.
Print the integer $K$ such that $|A - K| = |B - K|$.
If such an integer does not exist, print `IMPOSSIBLE` instead.
Print the integer $K$ such that $|A - K| = |B - K|$.
If such an integer does not exist, print `IMPOSSIBLE` instead.
Input
Input is given from Standard Input in the following format:
```
$A$ $B$
```
```
$A$ $B$
```
Output
Print the integer $K$ satisfying the condition.
If such an integer does not exist, print `IMPOSSIBLE` instead.
If such an integer does not exist, print `IMPOSSIBLE` instead.
Constraints
- All values in input are integers.
- $0 \leq A,\ B \leq 10^9$
- $A$ and $B$ are distinct.
- $0 \leq A,\ B \leq 10^9$
- $A$ and $B$ are distinct.
Sample 1 Input
2 16
Sample 1 Output
9
$|2 - 9| = 7$ and $|16 - 9| = 7$, so $9$ satisfies the condition.
Sample 2 Input
0 3
Sample 2 Output
IMPOSSIBLE
No integer satisfies the condition.
Sample 3 Input
998244353 99824435
Sample 3 Output
549034394