#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  ll a, b, s;
  cin >> a >> b >> s;
  ll ans = 0;
  for (ll h = 1; h <= a; ++h) {
    for (ll w = 1; w <= b; ++w) {
      if (h * w > s) break;
      ans += (a - h + 1) * (b - w + 1);
    }
  }
  cout << ans << '\n';
  return 0;
}