#include <stdio.h>

int main()
{
	int A, B, S;
	scanf("%d %d %d", &A, &B, &S);
	
	int h, w;
	long long ans = 0;
	for (w = 1; w <= A && w <= S; w++) {
		for (h = 1; h <= B && h * w <= S; h++) {
			ans += (long long)(A - w + 1) * (B - h + 1);
		}
	}
	printf("%lld\n", ans);
	fflush(stdout);
	return 0;
}