#include<bits/stdc++.h>

using namespace std;

using ll   = long long;     using ld   = long double;
using pll  = pair<ll, ll>;  using pld  = pair<ld, ld>;
using vll  = vector<ll>;    using vld  = vector<ld>;
using vpll = vector<pll>;   using vpld = vector<pld>;
using vvll = vector<vll>;   using vvld = vector<vld>;
template<class T> using min_queue = priority_queue<T, vector<T>, greater<T>>;
template<class T> using max_queue = priority_queue<T, vector<T>, less<T>>;

#define rep(i, a, b) for(ll i = (ll)a; i < (ll)b; i++)
#define irep(i, v) for(auto i = (v).begin(); i != (v).end(); i++)
#define SZ(v) (ll)(v).size()
#define ALL(v) (v).begin(), (v).end()
#define SHIFT(a) (1LL << (ll)a)
#define endl '\n'

const ll INF = 1e18;
const ll MOD = 1e9 + 7;
const ld EPS = 1e-10;
const ld PI  = M_PI;

ll power(ll x, ll y){ ll res = 1; while(y > 0){ if(y & 1){ res *= x; } x *= x; y >>= 1; } return res; }
bool in_grid(ll x, ll y, ll h, ll w){ return (0 <= x && x < h && 0 <= y && y < w); }
template<class T> void pvec(vector<T> &vec){ for(ll i = 0; i < (ll)vec.size(); i++){ if(i){ cout << " "; } cout << vec[i]; } cout << endl; }
template<class T1, class T2> void ppai(pair<T1, T2> &pai){ cout << pai.first << " " << pai.second << endl; }
template<class T> void pvvec(vector<vector<T>> &vec){ for(ll i = 0; i < (ll)vec.size(); i++){ for(ll j = 0; j < (ll)vec[i].size(); j++){ if(j){ cout << " "; } cout << vec[i][j]; } cout << endl; } }
template<class T> void asort(vector<T> &vec){ sort(ALL(vec)); }
template<class T> void rsort(vector<T> &vec){ sort(ALL(vec)); reverse(ALL(vec)); }





//using mint = modint<MOD>;

int main(){
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  srand((unsigned)time(NULL));
  cout << fixed << setprecision(20);

  ll a, b, s;
  cin >> a >> b >> s;

  ll ans = 0;

  for(ll i = 1; i <= s; i++){
    for(ll j = 1; j * j <= i; j++){
      if(i % j == 0){
        ll t = j, u = i / j;
        if(j * j == i){
          if(t <= a && u <= b) ans += (a - t + 1) * (b - u + 1);
        }
        else{
          if(t <= a && u <= b) ans += (a - t + 1) * (b - u + 1);
          if(u <= a && t <= b) ans += (a - u + 1) * (b - t + 1);
        }
      }
    }
  }

  cout << ans << endl;





  return 0;
}