#include <bits/stdc++.h>
using namespace std;
long long dp[(int)1e6 + 5];
long long factorize(long long n) {
  if (dp[n] != -1) return dp[n];
  long long ans = 0;
  for (long long i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (i * i != n)
        ans += 2;
      else
        ans++;
    }
  }
  dp[n] = ans;
  return ans;
}
int main() {
  long long a, b, c;
  cin >> a >> b >> c;
  memset(dp, -1, sizeof dp);
  long long m = 1 << 30;
  long long ans = 0;
  for (long long i = 1; i <= a; i++) {
    for (long long j = 1; j <= b; j++) {
      for (long long k = 1; k <= c; k++) {
        long long product = i * j * k;
        ans = (ans % m + (int)factorize(product) % m) % m;
      }
    }
  }
  cout << ans;
  return 0;
}
