#pragma once

#include<iostream>
#include<fstream>
#include<algorithm>
#include<vector>

using namespace std;

#define L 21
#define C 21
#define MM 49100

ifstream fin("diamant.in");
ofstream fout("diamant.out");

int dp[L*C][MM];  // dp[i][j] nr moduri in care din primele i elem obtii greutatea j
int N, M, X;

void bu(int n, int m, int x, int maxAbs) {
	int k = 0,c;
	dp[0][0] = 1;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			k++;
			for (int g = -maxAbs; g <= maxAbs; g++) {
				dp[k][g] = dp[k - 1][g] + dp[k - 1][g - i * j] + dp[k-1][g + i * j];
				c = dp[k][g];
			}
		}
	}
	fout << dp[n*m][x];
}

int main() {
	fin >> N >> M >> X;
	int maxAbs = N * (N + 1)*M*(M + 1) / 4;
	if (X<-maxAbs || X>maxAbs)
		fout << -1;
	else
		bu(N, M, X, maxAbs);
	return 0;

}