#include <bits/stdc++.h>
using namespace std;
int main() {
  int A, B, S;
  cin >> A >> B >> S;
  long long ans = 0;
  for (int i = 1; i <= S; i++) {
    for (int j = 1; i * j <= S; j++) {
      if ((A - i + 1) > 0 && (B - j + 1) > 0) {
        ans += (long long)(A - i + 1) * (B - j + 1);
      }
    }
  }
  cout << ans << endl;
}