from math import gcd

a, b, n = map(int, input().split())

if a == b:
    print(0)
    exit()
if a == 0:
    print(0)
    exit()

mod = 998244353
def lcm_base(x, y):
    '''
    最小公倍数を求める関数
    '''
    return (x * y) // gcd(x, y)

lcm = lcm_base(2 * a * b, a**2 + b**2)
min_l1 = (lcm // (2 * a * b)) * b
min_l2 = (lcm // (a**2 + b**2)) * b
max_l = max(min_l1, min_l2)
if max_l >= n:
    print(0)
    exit()

print((n - min_l1) * (n - min_l2) * 8 % mod)