
// Problem : F - Triangles
// Contest : AtCoder - Tokio Marine & Nichido Fire Insurance Programming Contest 2020
// URL : https://atcoder.jp/contests/tokiomarine2020/tasks/tokiomarine2020_f
// Memory Limit : 1024 MB
// Time Limit : 4000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

#include<bits/stdc++.h>
using namespace std;
typedef unsigned int ui;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef complex<double> cd;
typedef pair<int,int> pii;
typedef pair<int,ll > pil;
typedef pair<ll ,int> pli;
typedef pair<ll ,ll > pll;
typedef vector<int> vi;
typedef vector<ll > vl;
#define pque priority_queue
#define rep(i,l,r) for(i=(l);i<=(r);++i)
#define per(i,l,r) for(i=(l);i>=(r);--i)
#define REP(i,l,r) for(i=(l);i< (r);++i)
#define PER(i,l,r) for(i=(l);i> (r);--i)
#define mp make_pair
#define pb push_back
#define pf push_front
#define pob pop_back
#define pof pop_front
#define fi first
#define se second
#define bugf(...) fprintf(stderr,__VA_ARGS__);
#define bugs(x) cerr<<"    "<<(x);
#define bugx(x) cerr<<"    "<<(#x)<<" = "<<(x);
#define bugl cerr<<"\n";
#define bugL cerr<<"\n================================================\n";
#define bugt bugx(clock());bugl;
template<class IT>inline void cmax(IT &a,IT b){if(a<b)a=b;}
template<class IT>inline void cmin(IT &a,IT b){if(b<a)a=b;}
template<class IT>inline bool bmax(IT &a,IT b){if(a<b){a=b;return true;}else return false;}
template<class IT>inline bool bmin(IT &a,IT b){if(a>b){a=b;return true;}else return false;}
inline int gcd(int a,int b){
	int c;
	while(c=b){
		b=a%b;
		a=c;
	}
	return a;
}
ll ans;

inline void sol(int w,int h,int k){
	//bugL bugs("SOL") bugx(w) bugx(h) bugl
	int x,s,y,r,b=((k-1)<<1)+w;
	REP(x,1,w)per(s,min(h-2,b/x),0){
		//bugx(x) bugx(s) bugl
		r=(k<<1)-(2+x*s)+gcd(w,s);
		y=r/w+1;
		if(y*w-gcd(x,y)-gcd(w-x,y+s)>r)--y;
		cmin(y,h-(s+1));
		ans+=s?(y<<1):y;
	}
}
inline void ac(){
	int w,h,k;
	scanf("%d%d%d",&w,&h,&k);
	sol(w,h,k);
	sol(h,w,k);
	printf("%lld",ans<<1);
}
int main(){
	//freopen("a.in","r",stdin);
	//freopen("a.out","w",stdout);
	
	ac();
	return 0;
}
#undef pque
#undef rep
#undef per
#undef REP
#undef PER
#undef mp
#undef pb
#undef pf
#undef pob
#undef pof
#undef fi
#undef se
#undef bugs
#undef bugx
#undef bugl