#abc246d. [abc246_d]2-variable Function
[abc246_d]2-variable Function
Problem Statement
Given an integer , find the smallest integer that satisfies all of the conditions below.
- is greater than or equal to .
- There is a pair of non-negative integers such that .
Constraints
- is an integer.
Input
Input is given from Standard Input in the following format:
Output
Print the answer as an integer.
Sample Input 1
9
Sample Output 1
15
For any integer such that , there is no that satisfies the condition in the statement.
For , satisfies the condition.
Sample Input 2
0
Sample Output 2
0
itself may satisfy the condition.
Sample Input 3
999999999989449206
Sample Output 3
1000000000000000000
Input and output may not fit into a -bit integer type.