#include <bits/stdc++.h>
long long n, m, k, ans = 0, sum [100001] = {0};
using namespace std;
int main() {
	cin >> n >> m >> k;
	int num[n][m];
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			num[i][j] = lcm(i, j);
		}
	}
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			sum[num[i][j]]++;
			for (int a = 1; a <= k; ++a) {
				if (a % num[i][j] == 0 && a != num[i][j])
					sum[a]++;
			}
		}
	}
	for (int i = 1; i <= k; ++i) {
		ans += sum[i] * i;
	}
	cout << ans;
}