#include <bits/stdc++.h>
using namespace std;
string to_string(string s) { return '"' + s + '"'; }
string to_string(const char *s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> t) {
  return "(" + to_string(get<0>(t)) + ", " + to_string(get<1>(t)) + ", " +
         to_string(get<2>(t)) + ")";
}
template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += '}';
  return res;
}
void _debug() { cerr << '\n'; }
template <typename Head, typename... Tail>
void _debug(Head H, Tail... T) {
  cerr << ' ' << to_string(H);
  _debug(T...);
}
using ll = long long;
using ld = long double;
using ii = pair<int, int>;
using vi = vector<int>;
using vii = vector<ii>;
using vc = vector<char>;
using vb = vector<bool>;
using vll = vector<ll>;
int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(9);
  const ll mod = 1073741824;
  ll ans = 0;
  int a, b, c;
  cin >> a >> b >> c;
  vll divisors(a * b * c + 1);
  for (int i = 1; i <= a * b * c; ++i) {
    ll div = 1;
    int cur = i;
    for (int d = 2; d * d <= cur; ++d) {
      if (cur % d == 0) {
        ll curdiv = 1;
        while (cur % d == 0) {
          cur /= d;
          ++curdiv;
        }
        div *= curdiv;
      }
    }
    if (cur > 1) div *= 2;
    divisors[i] = div;
  }
  for (int i = 1; i <= a; ++i) {
    for (int j = 1; j <= b; ++j) {
      for (int k = 1; k <= c; ++k) {
        ans = (ans + divisors[i * j * k]) % mod;
      }
    }
  }
  cout << ans;
}
