#include <bits/stdc++.h>
using namespace std;
const int N = 2e6 + 6, oo = 1e9, MOD = 1073741824;
int a, b, c;
long long sum;
int div(int x) {
  int cnt = 0;
  for (int i = 1; i * i <= x; i++)
    if (!(x % i)) {
      if (x / i != i) cnt++;
      cnt++;
    }
  return cnt;
}
int main() {
  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++) sum = sum % MOD + div(i * j * k) % MOD;
  cout << sum << endl;
  return 0;
}
