#include <bits/stdc++.h>
using namespace std;
int long nodiv(int long n) {
  int ans = 1;
  for (int long i = 2; i * i <= n; i++) {
    int cnt = 0;
    while (n % i == 0) {
      n /= i;
      cnt++;
    }
    ans *= cnt + 1;
  }
  if (n > 1) ans *= 2;
  return ans;
}
int main() {
  int long long n = 0, a, b, c;
  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++) n += nodiv(i * j * k);
  cout << n << endl;
}
