#include <bits/stdc++.h>
using namespace std;
int a, b, c, d[1000005], i, j, k, ans;
int main() {
  cin >> a >> b >> c;
  for (i = 1; i <= 1e6; i++)
    for (j = i; j <= 1e6; j += i) d[j]++;
  for (i = 1; i <= a; i++)
    for (j = 1; j <= b; j++)
      for (k = 1; k <= c; k++) ans += d[i * j * k];
  cout << ans;
}
