#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define INF 1000000000000000000
#define MOD 998244353
#define MAX 1000000

ll gcd(ll a,ll b){
  while(a%b!=0){
    ll tmp=a%b;
    a=b;
    b=tmp;
  }
  return b;
}

int main(){
  ll a,b,N;
  cin>>a>>b>>N;
  if(a==b||a==0||b==0){
    cout<<0<<'\n';
    return 0;
  }
  ll x1=a;
  ll y1=b;
  ll x2,y2;
  //(b*i-a*j)/(a*i+b*j)=a/b
  //b*(b*i-a*j)=a*(a*i+b*j)
  //(b*b-a*a)*i=2*a*b*j
  ll i=2*a*b;
  ll j=b*b-a*a;
  ll g=gcd(i,j);
  i/=g;
  j/=g;
  ll X=a*i+b*j;
  ll Y=b*i;
  ll ans=(max<ll>(0,N-X)%MOD)*(max<ll>(0,N-Y)%MOD)%MOD;
  ans=8*ans%MOD;
  cout<<ans<<'\n';
}