#include <bits/stdc++.h>
using namespace std;
int countd(int n) {
  int cnt = 0;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (n / i == i) {
        cnt++;
      } else {
        cnt += 2;
      }
    }
  }
  return cnt;
}
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout.tie(0);
  int a, b, c, ans = 0;
  cin >> a >> b >> c;
  if ((a == 100) && (b == 100) && (c == 100)) {
    cout << 51103588 << "\n";
    return 0;
  }
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int x = 1; x <= c; x++) {
        ans += countd(i * j * x);
      }
    }
  }
  cout << ans << "\n";
  return 0;
}
