#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
using mint=modint998244353;
mint f[2000010], invf[2000010];
void fac(int n){
    f[0]=1;
    for(ll i=1; i<=n; i++) f[i]=f[i-1]*i;
    invf[n]=f[n].inv();
    for(ll i=n-1; i>=0; i--) invf[i]=invf[i+1]*(i+1);
}
mint comb(int x, int y){
    if(!(0<=y && y<=x)) return 0;
    return f[x]*invf[y]*invf[x-y];
}

int main()
{
    int a, b;
    cin>>a>>b;
    ll n;
    cin>>n;
    if(a==b || a==0){
        cout<<0<<endl;
        return 0;
    }
    int g=gcd(2*a*b, b*b-a*a);
    int s=2*a*b/g, t=(b*b-a*a)/g;
    int x=s*a+t*b, y=s*b;
    mint ans=mint(n-x)*mint(n-y);
    ans*=8;
    cout<<ans.val()<<endl;
    return 0;
}