#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <array>
#include <unordered_map>
#include <unordered_set>
#include <initializer_list>
#include <tuple>

using namespace std;


using vi = vector<int>;
using vii = vector<vi>;
using vs = vector<string>;
using vss = vector<vs>;
using vb = vector<bool>;
using vbb  = vector<vb>;
using ii = pair<int, int>;
using vpi = vector<ii>;
using vpii = vector<vpi>;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using table = unordered_map<unsigned long, int>;
using pll = pair<ll,ll>;
using vpl = vector<pll>;
using vpll = vector<vpl>;

#define f first
#define s second

#define forn(i, n) for(int i = 0; i < n; i++)
#define fore(i, a, b) for(int i = a; i <= b; i++)
#define for1n(i, n) for(int i = 1; i <= n; i++)
#define rof(i, n) for(int i = n-1; i >= 0; i--)
#define rofe(i, a, b) for(int i = b; i >= a; i--)
#define all(x) x.begin(), x.end()
#define dsc(type) greater<type>

#define Flag cout << "Reached here.\n"
#define FASTIO ios::sync_with_stdio(0); cin.tie(0);

#define pb push_back
#define pbb pop_back
#define sz size
#define rsz resize
#define rsv reserve
#define ins insert

#define lb(a, val) lower_bound(all(a), val);
#define ub(a, val) upper_bound(all(a), val);

#define onec(x) __builtin_popcount(x)
#define end0(x) __builtin_clz(x)
#define beg0(x) __builtin_ctz(x)

#define MAX 1000000005
#define MIN -MAX

#define mod 1000000007LL

#define clr(x, y) memset(x, y, sizeof(x))

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }

int dx[] = {0, 1, -1, 0};
int dy[] = {1, 0, 0, -1};

void init() {
    #ifndef ONLINE_JUDGE
    freopen("output.txt", "w", stdout);
    freopen("input.txt", "r", stdin);
    #endif
}

ll binpow(ll a, ll b) {
    a %= mod;
    ll res = 1;
    while (b > 0) {
        if (b & 1) res *= a, res %= mod;
        a *= a, a %= mod;
        b >>= 1;
    }
    return res;
}

vi fct(ll n) {
    vi fac;
    while(n%2 == 0) n /= 2, fac.pb(2);
    for(int i = 3; i * i <= n; i += 2) 
        while(n%i == 0) fac.pb(i), n /= i;
    if(n > 1) fac.pb(n);
    return fac;
}

ll gcd(ll a, ll b) {
   if (b == 0) return a;
   return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
    return (a*b) / gcd(a, b);
}

using lll = __int128;

void solve() {
    ll a, b, s;
    cin >> a >> b >> s;
    
    auto rsm = [&](lll l, lll r) -> lll {
        // l--;
        // cout << r << ' ' << ((r*(r+1))/2) << ' ' << l << ' ' << ((l*(l+1))/2) << '\n';
        return ((r*(r+1))/2) - ((l*(l+1))/2);
    };

    lll ans = 0;
    for(lll i = 1; i <= min(s, a); i++) {
        lll d = min((lll) b, s/i);
        lll cur = (rsm(b-d, b)) * (a-i+1);
        // cout << d << ' ' << (ll) rsm(b-d, b) << ' ' << (ll) (a-i+1) << '\n';
        ans += cur;
    }
    cout << (unsigned long long) ans << '\n';
}

int main() {
    //Sublime
    // init();
    // FASTIO
    // Flag;
    solve();
}