#include <bits/stdc++.h>
using namespace std;
long long sol[1000001]{0};
long long div(long long n) {
  long long sum = 0;
  if (sol[n] != 0)
    return sol[n];
  else if (n == 1)
    sum++;
  else
    for (long long i = 1; i * i <= n; i++) {
      if (i * i == n)
        sum++;
      else if (n % i == 0)
        sum += 2;
    }
  sol[n] = sum;
  return sum;
}
int main() {
  long long a, b, c, ans{0};
  cin >> a >> b >> c;
  for (long long i = 1; i <= a; i++)
    for (long long j = 1; j <= b; j++)
      for (long long k = 1; k <= c; k++) ans += div(i * j * k);
  cout << ans % 1073741824 << '\n';
  return 0;
}
