#include <iostream>
#include <string>
#include <set>
#include <algorithm>


using namespace std;
using ll = long long;


int main() {
    ll W, H, S; cin >> W >> H >> S;
    ll ans = 0;
    for (int w=1; w<=min(S, W); w++) {
        ll res = 0;
        for (int h=1; h<=min(H, S/w); h++) {
            res += H - h + 1;
        }
        ans += res*(W - w + 1);
    }
    cout << ans << endl;
}