#include <bits/stdc++.h>
using namespace std;
int arr[1000100];
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  ;
  int a, b, c, s = 0;
  cin >> a >> b >> c;
  for (int i = 1; i <= 1e6; i++)
    for (int j = i; j <= 1e6; j += i) arr[j]++;
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++)
      for (int k = 1; k <= c; k++) s += arr[i * j * k];
  cout << s;
  return 0;
}
