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

int main(){
    long long A, B, S, ans = 0;
    cin >> A >> B >> S;
    vector<vector<int>> tb(S + 1);
    for(int i = 1; i <= S; i++){
        for(int j = i; j <= S; j+=i) tb[j].push_back(i);
        for(auto &&v:tb[i]) ans += max(0ll, A - v + 1) * max(0ll, B - i / v + 1);
    }
    cout << ans << endl;
}