#include <bits/stdc++.h>
using namespace std;
int pf(int n) {
  int cnt;
  long long div = 1;
  for (int i = 2; i * i <= n; i++)
    if (n % i == 0) {
      cnt = 0;
      while (n % i == 0) {
        cnt++;
        n /= i;
      }
      div = (div * (cnt + 1)) % 1073741824;
    }
  if (n > 1) div = (div * 2) % 1073741824;
  return div;
}
int main() {
  ios::sync_with_stdio(false);
  int a, b, c;
  long long ans = 0;
  cin >> a >> b >> c;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) {
        ans = (ans + pf(i * j * k)) % 1073741824;
      }
  cout << ans << endl;
  return 0;
}
