#include <bits/stdc++.h>
using namespace std;
int no_of_divisors(int n) {
  int count = 0;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (i * i == n) {
        count++;
      } else {
        count += 2;
      }
    }
  }
  return count;
}
int main() {
  int a, b, c, sum = 0;
  cin >> a >> b >> c;
  map<int, int> M;
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int k = 1; k <= c; k++) {
        if (M[i * j * k] == 0) {
          M[i * j * k] = no_of_divisors(i * j * k);
          sum += M[i * j * k];
        } else {
          sum += M[i * j * k];
        }
      }
    }
  }
  cout << sum << endl;
  return 0;
}
