#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<bool> prime(1000001, true);
ll mod = 1073741824;
void seive() {
  prime[0] = false;
  prime[1] = false;
  for (ll i = 2; i * i <= 1000000; i++) {
    if (prime[i]) {
      for (ll j = i * i; j <= 1000000; j += i) {
        prime[j] = false;
      }
    }
  }
}
ll divisors(ll x) {
  if (prime[x]) {
    return 2;
  } else {
    ll ans = 1;
    for (ll i = sqrt(x); i >= 2; i--) {
      ll e = 0;
      if (prime[i] && x % i == 0) {
        while (x % i == 0) {
          e++;
          x = x / i;
        }
      }
      ans = ans * (e + 1);
    }
    if (prime[x]) {
      ans = ans * 2;
    }
    return ans;
  }
}
void solveCP311() {
  ll a, b, c;
  cin >> a >> b >> c;
  ll ans = 0;
  for (ll i = 1; i <= a; i++) {
    for (ll j = 1; j <= b; j++) {
      for (ll k = 1; k <= c; k++) {
        ans = (ans + divisors(i * j * k)) % mod;
      }
    }
  }
  cout << ans % mod << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  seive();
  ll t = 1;
  while (t--) {
    solveCP311();
  }
  return 0;
}
