#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int a, b, c;
  cin >> a >> b >> c;
  vector<int> divs(1000009);
  int n = a * b * c + 9;
  for (int i = 1; i < n; i++)
    for (int j = i; j < n; j += i) divs[j]++;
  int ans = 0;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) ans += divs[i * j * k];
  cout << ans;
  return 0;
}
