#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
long long gcd(long long a, long long b){
  if (b == 0){
    return a;
  } else {
    return gcd(b, a % b);
  }
}
int main(){
  long long a, b, N;
  cin >> a >> b >> N;
  if (a == 0 || a == b){
    cout << 0 << endl;
  } else {
    long long k = a * a + b * b;
    long long l = 2 * a * b;
    long long g = gcd(k, l);
    k /= g;
    l /= g;
    long long A = (N - b * k) % MOD;
    long long B = (N - b * l) % MOD;
    cout << A * B % MOD * 8 % MOD << endl;
  }
}