#include <bits/stdc++.h>
using namespace std;
const int MOD = (1 << 30) - 1, MAX = 1e6 + 2;
int divisors[MAX];
int getDivisors(int n) {
  int cnt = 0;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ++cnt;
      if (i * i != n) ++cnt;
    }
  }
  return cnt;
}
int main() {
  int a, b, c;
  long long sum = 0;
  cin >> a >> b >> c;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) {
        long long tmp = 1ll * i * j * k;
        if (divisors[tmp] == 0) divisors[tmp] = getDivisors(tmp);
        sum += divisors[tmp];
      }
  cout << sum % MOD;
}
