#pragma GCC optimize("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")


#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define SZ(x) ((int)((x).size()))

template <typename T1, typename T2>
string print_iterable(T1 begin_iter, T2 end_iter, int counter) {
    bool done_something = false;
    stringstream res;
    res << "[";
    for (; begin_iter != end_iter and counter; ++begin_iter) {
        done_something = true;
        counter--;
        res << *begin_iter << ", ";
    }
    string str = res.str();
    if (done_something) {
        str.pop_back();
        str.pop_back();
    }
    str += "]";
    return str;
}

vector<int> SortIndex(int size, std::function<bool(int, int)> compare) {
    vector<int> ord(size);
    for (int i = 0; i < size; i++) ord[i] = i;
    sort(ord.begin(), ord.end(), compare);
    return ord;
}

template <typename T>
bool MinPlace(T& a, const T& b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <typename T>
bool MaxPlace(T& a, const T& b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

template <typename S, typename T>
ostream& operator <<(ostream& out, const pair<S, T>& p) {
    out << "{" << p.first << ", " << p.second << "}";
    return out;
}

template <typename T>
ostream& operator <<(ostream& out, const vector<T>& v) {
    out << "[";
    for (int i = 0; i < (int)v.size(); i++) {
        out << v[i];
        if (i != (int)v.size()-1) out << ", ";
    }
    out << "]";
    return out;
}

template<class TH>
void _dbg(const char* name, TH val){
    clog << name << ": " << val << endl;
}
template<class TH, class... TA>
void _dbg(const char* names, TH curr_val, TA... vals) {
    while(*names != ',') clog << *names++;
    clog << ": " << curr_val << ", ";
    _dbg(names+1, vals...);
}

#if DEBUG && !ONLINE_JUDGE
    ifstream input_from_file("input.txt");
    #define cin input_from_file

    #define dbg(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
    #define dbg_arr(x, len) clog << #x << ": " << print_iterable(x, x+len, -1) << endl;
#else
    #define dbg(...)
    #define dbg_arr(x, len)
#endif

///////////////////////////////////////////////////////////////////////////
//////////////////// DO NOT TOUCH BEFORE THIS LINE ////////////////////////
///////////////////////////////////////////////////////////////////////////


LL solve(int W, int H, int K) {
    vector<int> preg(W);
    for (int i = 0; i < W; i++) preg[i] = __gcd(i, H);
    
    LL res = 0;
    for (int y = 1; y < H; y++) {
        for (int x1 = 1; x1 < W; x1++) {
            if ((H-y)*x1 > 2*K + 2*H) break;
            LL U = 2*K - (H-y)*x1;
            if (((LL)y)*x1 <= U) {
                res += 2*(x1-1) + 1;
                continue;
            }
            int low = 1;
            if (y <= U) {
                low = U/y;
                res += 2*(low-1);
            }
            int g = __gcd(x1, y);
            for (int x2 = low; x2 <= x1; x2++) {
                if (x1 != x2 and (H-y)*x1 + y*x2 > 2*K+g + min(x2, H-y) + min(x1-x2, H)) x2 = x1;
                if ((LL)y*x2 > 1e6) break;
                LL c = (H-y)*x1 + y*x2 - (g + __gcd(x2, H-y) + preg[x1-x2]) + 2;
                if (c <= 2*K) res += (x1 != x2)?2:1;
            }
        }
    }
    return res;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0); // Remove in problems with online queries!

    int W, H, K;
    cin >> W >> H >> K;
    LL ris1 = solve(W, H, K);
    LL ris2 = solve(H, W, K);
    cout << 2*(ris1+ris2) << endl;
}


Measured memory_bytes: 4008