/*
不确定题目的运行时间，但是全部取最大值没法在1s内跑完。
*/
#include <bits/stdc++.h>

using namespace std;

const int inf = 0x3f3f3f3f;
int n, m, k;
int f[60][60][60];

int dfs(int n, int m, int k)
{
    if (n * m == k || k == 0) return f[n][m][k] = 0;


    if (n * m < k) return f[n][m][k] = inf / 2;

    if (f[n][m][k] != inf) return f[m][n][k] = f[n][m][k]; // 对称记忆，速度快一倍

    int &res = f[n][m][k];
    for (int i = 1, j; i <= n + m - 2; i ++ )
    {
        int A, B, ia, ib;
        if (i >= 1 && i <= n - 1) j = m, ia = i, ib = n - ia;
        else j = n, ia = i - n + 1, ib = m - ia;
        A = min(ia * j, ib * j);
        B = max(ia * j, ib * j);

        for (int K = 0; K <= k; K ++ )
        {
            // cout << "A: " << A / j << ' ' << j << ' ' << K << ' ';
            // cout << "B: " << B / j << ' ' << j << ' ' << k - K << ' ' << endl;
            res = min(dfs(ia, j, K) + dfs(ib, j, k - K) + j * j, res);
        }
    }
    return res;
}

int main()
{
    memset(f, 0x3f, sizeof f);
    cin >> n >> m >> k;
    cout << dfs(n, m, k) << endl;
    return 0;

}