#include <bits/stdc++.h>
using namespace std;
int d(int ind) {
  int c = 0;
  for (int i = 1; i <= sqrt(ind); i++) {
    if (ind % i == 0) {
      if (i * i == ind)
        c++;
      else
        c += 2;
    }
  }
  return c;
}
int main() {
  int a, b, c;
  map<int, int> mp;
  cin >> a >> b >> c;
  long long ans = 0, mod = 1073741824;
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int k = 1; k <= c; k++) {
        int x = i * j * k;
        if (mp.count(x) == 0) mp[x] = d(x);
        ans = (ans % mod + mp[x] % mod) % mod;
      }
    }
  }
  cout << ans % mod;
  return 0;
}
