#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long a, b, c;
  cin >> a >> b >> c;
  long long m = a * b * c;
  long long arr[m + 1];
  memset(arr, 0, sizeof(arr));
  for (long long i = 1; i <= m; i++) {
    for (long long j = i; j <= m; j += i) arr[j]++;
  }
  long long sum = 0;
  for (long long i = 1; i <= a; i++) {
    for (long long j = 1; j <= b; j++) {
      for (long long k = 1; k <= c; k++) {
        sum = (sum % 1073741824 + arr[i * j * k] % 1073741824) % 1073741824;
      }
    }
  }
  cout << sum;
  return 0;
}
