#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;
using ll = long long;

int main(){

    ll A, B, S, ans=0;
    cin >> A >> B >> S;
    vector<vector<ll>> p(S+1);
    for (int i=1; i<=S; i++){
        for (int j=i; j<=S; j+=i) p[j].push_back(i);
    }

    for (int i=1; i<=S; i++){
        for (auto x : p[i]) ans += max(0LL, A-x+1) * max(0LL, B-i/x+1);
    }

    cout << ans << endl;

    return 0;
}