#include <bits/stdc++.h>
using namespace std;

// Template
// ==============================================
    // pbds
    // #include <ext/pb_ds/assoc_container.hpp>
    // #include <ext/pb_ds/tree_policy.hpp>
    // using namespace __gnu_pbds;
    // template<typename T, typename comp = less<T>>
    // using ordered_set =  tree<T, null_type, comp, rb_tree_tag, tree_order_statistics_node_update>;

    // Debugging
    #ifdef LOCAL
    #include "debug.h"
    #else
    #define debug(...)
    #define see(x)
    #endif

    typedef long long ll;
    typedef vector<int> VI;
    typedef vector<long long> VLL;
    typedef vector<bool> VB;
    typedef vector<vector<int>> VVI;
    typedef pair<int, int> PI;
    typedef pair<ll, ll> PLL;
    typedef vector<pair<int, int>> VPI;

    #define pb push_back
    #define ff first
    #define ss second
    #define mp make_pair
    #define all(a) a.begin(), a.end()
    #define revall(a) a.rbegin(), a.rend()

    #define loop(i, s, e) for (int i = s; i < e; ++i)
    #define inp(v) for (auto& x : v) cin >> x
    #define outp(v) for (int i = 0, n = v.size(); i < n; ++i) cout << v[i] << " \n"[i == n - 1]

    #define nl "\n"
    #define yep cout << "YES\n"
    #define nope cout << "NO\n"

    #define INF (int) 1e9
    #define INFL (ll) 1e18
    // #define MOD 998244353
    #define MOD 1000000007
    #define MAXN 100002
// =============================================

void solve(int tc)
{
    ll a, b, s; cin >> a >> b >> s;

    ll ans = 0;
    loop(i, 1, s + 1)
    {
        for (ll x = 1; x * x <= i; ++x)
        {
            if (i % x) continue;

            ll y = i / x;

            ans += max(0LL, a - x + 1) * max(0LL, b - y + 1);
            if (x != y) ans += max(0LL, a - y + 1) * max(0LL, b - x + 1);
        }
    }

    cout << ans << nl;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    
    int t = 1;
    // cin >> t;
    int x = t;
    while(t--) solve(x - t);
    
    #ifdef LOCAL
    cerr << "Execution time: " << 1000.f * clock() / CLOCKS_PER_SEC << " ms." << nl;
    #endif
    
    return 0;
}