#include <bits/stdc++.h>
using namespace std;
map<int, int> res;
int arr[1000010] = {0};
long long cal(long long num) {
  if (arr[num] > 0) return arr[num];
  for (long long i = 1; i * i <= num; i++) {
    if (num % i == 0) {
      if (i * i == num)
        arr[num] += 1;
      else
        arr[num] += 2;
    }
  }
  return arr[num];
}
int main() {
  int a, b, c;
  arr[1] = 1;
  arr[2] = 2;
  long long ans = 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 = i * j * k;
        ans += cal(tmp);
      }
    }
  }
  cout << ans;
  return 0;
}
