#include <bits/stdc++.h>
using namespace std;
long long dp[1000005];
long long solve(long long n) {
  long long prod = 1;
  long long temp = n;
  for (long long i = 2; i * i <= n; i++) {
    long long cnt = 0;
    while (n % i == 0) {
      n /= i;
      cnt++;
    }
    prod = prod * (cnt + 1);
  }
  if (n > 1) prod *= 2;
  return dp[temp] = prod;
}
int32_t main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  long long t = 1;
  while (t--) {
    long long a, b, c;
    cin >> a >> b >> c;
    memset(dp, -1, sizeof(dp));
    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++) {
          if (dp[i * j * k] == -1) dp[i * j * k] = solve(i * j * k);
          ans += dp[i * j * k];
          ans %= 1073741824;
        }
    cout << ans;
  }
  return 0;
}
