#include <iostream>
#include <cstdio>
using namespace std;
int n,m,x,dp[88205],v[405],nr=0;
void facere()
{
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
    {
        v[++nr]=i*j;
        dp[i*j+44100]++;
    }
}
void citire()
{
    scanf("%d%d%d",&n,&m,&x);
    facere();
    for(int i=1;i<=nr;i++)
        for(int j=0;j<=88200;j++)
    {
        if(dp[j]!=0)
        {
            dp[j-v[i]]++;
            dp[j+v[i]]++;
            dp[j]++;
        }
    }
    printf("%d",dp[x+44100]/3-1);
}
int main()
{
    freopen("diamant.in","r",stdin);
    freopen("diamant.out","w",stdout);
    citire();
  //  cout << "Hello world!" << endl;
    return 0;
}