#include <bits/stdc++.h>
using namespace std;
vector<int> d;
int countDivisors(int n) {
  if (d[n] != 0) return d[n];
  int res = 0;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (n / i == i)
        res++;
      else
        res += 2;
    }
  }
  d[n] = res;
  return res;
}
void solve() {
  int a, b, c;
  cin >> a >> b >> c;
  d = vector<int>(a * b * c + 1, 0);
  int ans = 0;
  for (auto i = (1); i < (a + 1); i++)
    for (auto j = (1); j < (b + 1); j++)
      for (auto k = (1); k < (c + 1); k++) ans += countDivisors(i * j * k);
  cout << ans % 1073741824 << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  while (t--) solve();
  return 0;
}
