#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
namespace my{
#define LL(...) ll __VA_ARGS__;lin(__VA_ARGS__)
#define FO(n) for(ll ij=n;ij-->0;)
#define FOR(i,...) for(auto[i,i##stop,i##step]=range(0,__VA_ARGS__);i<i##stop;i+=i##step)
#define fo(i,...) FO##__VA_OPT__(R)(i __VA_OPT__(,__VA_ARGS__))
#define schrodinger(p,c) (p?c:remove_cvref_t<decltype(c)>{})
#define single_testcase void solve();}int main(){my::io();my::solve();}namespace my{
void io(){cin.tie(nullptr)->sync_with_stdio(0);cout<<fixed<<setprecision(15);}
using ll=long long;
constexpr auto range(ll s,ll b){ll a=0;if(s)swap(a,b);return array{a-s,b,1-s*2};}
constexpr auto range(ll s,ll a,ll b,ll c=1){return array{a-s,b,(1-s*2)*c};}
const string newline{char(10)};
const string space{char(32)};
auto max(auto...a){return max(initializer_list<common_type_t<decltype(a)...>>{a...});}

void lin(auto&...a){(cin>>...>>a);}
void pp(const auto&...a){ll n=sizeof...(a);((cout<<a<<schrodinger(--n>0,space)),...);cout<<newline;}

single_testcase
void solve(){
  LL(A,B,S);

  ll ans=0;
  fo(a,1,S+1){
    fo(b,1,S/a+1){
      if(a>A||b>B)continue;
      ans+=max((A-a+1)*(B-b+1),0);
    }
  }
  pp(ans);
}}