typedef long long ll;
typedef long double ld;
#include <bits/stdc++.h>
using namespace std;
#define int long long

signed main(){
    ll a,b,s;
    std::cin >> a>>b>>s;
    ll ans = 0;
    for (int i = 1; i <= a; i++) {
        for (int j = 1; j <= s/i; j++) {
            ans += max(0ll,(a-i+1)*(b-j+1));
        }
    }
    std::cout << ans << std::endl;
}