#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
typedef long double ld;
const int inf=1e9+7;
const ll longinf=1LL<<60;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
#define F first
#define S second

const int mx=1000010;
const ll mod=1e9+7;


int main(){
  ll n,m,d;
  cin >> n >> m >> d;
  ld ans = 2 * (n-d) * (m-1);
  ans /= n;
  ans /= n;
  if(d==0) ans/=2;
  cout << fixed << setprecision(10) << ans << endl;
  return 0;
}
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define INF 1LL<<62
#define inf 1000000007 
const int MAX = 510000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
int main() {
	ll h,w,k;
	cin>>h>>w>>k;
    COMinit();	
	ll ans=0;
	ll H=(h-1)*h*(h+1)/6%inf*w%inf*w%inf;
	H*=COM(h*w-2,k-2);
	H%=inf;
	ll W=(w-1)*w*(w+1)/6%inf*h%inf*h%inf;
	W*=COM(h*w-2,k-2);
	W%=inf;
	ans+=H+W;
	ans%=inf;
    cout <<ans;
    // 計算例
//    cout << COM(100000, 50000) << endl;	
	// your code goes here
	return 0;
}