#include <bits/stdc++.h>
using namespace std;
int main() {
  long long sum = 0;
  int d[1000000 + 1] = {0};
  for (int i = 1; i <= 1000000; i++) {
    for (int j = i; j <= 1000000; j += i) {
      d[j]++;
    }
  }
  int a, b, c;
  cin >> a >> b >> c;
  for (auto(i) = (1); (i) < (a + 1); ++(i))
    for (auto(j) = (1); (j) < (b + 1); ++(j))
      for (auto(k) = (1); (k) < (c + 1); ++(k))
        sum = (sum + d[i * j * k]) % 1073741824;
  cout << sum % 1073741824;
  return 0;
}
