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#include<bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define REP(i, a) FOR(i, 0, a - 1)
#define ST first
#define ND second
#define V vector
#define RS resize
#define EB emplace_back
#define ALL(a) a.begin(), a.end()
#define S(a) (int)a.size()

template<class T> void db(T a) { cerr << a; }
template<class L, class R> void db(pair<L, R> a) { cerr << "(" << a.ST << ", " << a.ND << ")"; }
void db(V<pair<int, int> > v) { cerr << "\n{\n"; REP(i, S(v)) cerr << "    " << i << ": ", db(v[i]), cerr << "\n"; cerr << "}"; }
template<class T> void db(V<T> v) { cerr << "{"; REP(i, S(v)) cerr << (i != 0 ? ", " : ""), db(v[i]); cerr << "}"; }
template<class T> void dump(const char *s, T a) { cerr << s << ": "; db(a); cerr << "\n"; }
template<class T, class... TS> void dump(const char *s, T a, TS... x)
{ while(*s != ',') cerr<< *s++; cerr << ": "; db(a); dump(s + 1, x...); }

#ifdef DEBUG
#define DB(...) dump(#__VA_ARGS__, __VA_ARGS__); 
#else
#define DB(...)
#endif

using LL = long long;
using PII = pair<int, int>;
using VI = V<int>;
using VLL = V<LL>;
using VVI = V<VI>;
using VPII = V<PII>;

VPII data =
{
    {0, 1},
    {3, 4},
    {5, 12},
    {8, 15},
    {20, 21},
    {7, 24},
    {12, 35},
    {9, 40},
    {28, 45},
    {48, 55},
    {33, 56},
    {11, 60},
    {16, 63},
    {65, 72},
    {36, 77},
    {39, 80},
    {13, 84},
    {60, 91},
    {20, 99},
    {88, 105},
    {15, 112},
    {44, 117},
    {119, 120},
    {85, 132},
    {51, 140},
    {24, 143},
    {17, 144}
};

unsigned int X, Y, k;

void remove_too_long(VPII &ang)
{
    VPII copy;
    REP(i, S(ang))
        if(ang[i].ST * ang[i].ST + ang[i].ND * ang[i].ND <= k * k && ang[i].ST <= X && ang[i].ND <= Y)
            copy.EB(ang[i]);
    ang = copy;
}

void add_swapped(VPII &ang)
{
    VPII to_add;
    REP(i, S(ang))
        to_add.EB(ang[i].ND, ang[i].ST);
    REP(i, S(to_add))
        ang.EB(to_add[i]);
}

void add_reversed(VPII &ang)
{
    VPII to_add;
    REP(i, S(ang))
    {
        if(ang[i].ST != 0)
            to_add.EB(-ang[i].ST, ang[i].ND);
        if(ang[i].ND != 0)
            to_add.EB(ang[i].ST, -ang[i].ND);
        if(ang[i].ST != 0 && ang[i].ND != 0)
            to_add.EB(-ang[i].ST, -ang[i].ND);
    }
    REP(i, S(to_add))
        ang.EB(to_add[i]);
}

void angle_sort(VPII &ang)
{
    sort(ALL(ang), [](PII i, PII j)
    {
        REP(q, 2)
        {
            if(i.ND >= 0 && j.ND < 0)
                return (q == 0);
            swap(i, j);
        }

        return i.ST * j.ND - i.ND * j.ST > 0;
    });
}

VPII angles;

void construct_angles()
{
    int size = 0;
    if(k <= 15)
        size = 3;
    else if(X <= 150 && Y <= 150)
        size = 27;
    else if(k <= 100)
        size = 17;

    angles = VPII(data.begin(), data.begin() + size);
    remove_too_long(angles);
    add_swapped(angles);
    add_reversed(angles);
    angle_sort(angles);
}

unsigned int ans = 0;
void backtrack(int x = 0, int y = 0, int mx = 0, int my = 0, int Mx = 0, int My = 0, int pos = 0, int len = 0)
{
    if(Mx - mx >= X)
        return;
    if(My - my >= Y)
        return;

    if(x == 0 && y == 0 && len != 0)
    {
        if(len > 2)
            ans += (X - (Mx - mx)) * (Y - (My - my));
        return;
    }

    int _x, _y;
    while(pos < S(angles))
    {
        _x = x + angles[pos].ST;
        _y = y + angles[pos].ND;
        backtrack(_x, _y, min(mx, _x), min(my, _y), max(Mx, _x), max(My, _y), ++pos, len + 1);
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> X >> Y >> k;

    construct_angles();
    backtrack();

    cout << ans << "\n";
}