# Task
 Round the given number `n` to the nearest multiple of `m`.
 If `n` is exactly in the middle of 2 multiples of m, return `n` instead.
# Example
 For `n = 20, m = 3`, the output should be `21`.
 For `n = 19, m = 3`, the output should be `18`.
 For `n = 50, m = 100`, the output should be `50`.
# Input/Output
 - `[input]` integer `n`
 `1 ≤ n < 10^9.`
 - `[input]` integer `m`
 `3 ≤ m < 109`.
 - `[output]` an integer
from math import gcd, ceil
def rounding(n,m):
    return round(n/m)*m if n != ((n//m)*m + ceil(n/m)*m)/2 else n
from math import gcd, ceil
def rounding(n,m):
    return round(n/m)*m if n != ((n//m)*m + ceil(n/m)*m)/2 else n