#include <bits/stdc++.h>
const int N = 1e6 + 7;
const int MOD = 1073741824;
long long freq[N];
int main() {
  using namespace std;
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  long long a, b, c;
  cin >> a >> b >> c;
  for (int i = 1; i < N; ++i) {
    for (int j = 1; i * j < N; ++j) {
      freq[i * j]++;
    }
  }
  long long sum = 0;
  for (int i = 1; i <= a; ++i) {
    for (int j = 1; j <= b; ++j) {
      for (int k = 1; k <= c; ++k) {
        sum += freq[i * j * k];
        sum %= MOD;
      }
    }
  }
  cout << sum << '\n';
  return 0;
}
