#include <bits/stdc++.h>
using namespace std;
long long dp[1000001] = {0};
int32_t main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  long long t = 1;
  while (t--) {
    for (long long i = 1; i <= 1000000; i++)
      for (long long j = i; j <= 1000000; j += i) dp[j]++;
    long long a, b, c;
    cin >> a >> b >> c;
    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++)
          ans = (ans + dp[i * j * k]) % 1073741824;
    cout << ans << '\n';
  }
  return 0;
}
