#include <bits/stdc++.h>
using namespace std;
long int func(long int number) {
  long int sqrT = sqrt(number);
  long int ans = 0;
  for (long int i = 1; i <= sqrT; i++)
    if (number % i == 0)
      if (i == sqrT && number / i == sqrT)
        ans++;
      else
        ans += 2;
  return ans;
}
int main() {
  long int nod[1000001];
  for (long int i = 0; i < 1000001; i++) nod[i] = -1;
  nod[1] = 1;
  nod[2] = 2;
  long int ans = 0;
  long int a, b, c;
  cin >> a >> b >> c;
  for (long int i = 1; i <= a; i++)
    for (long int j = 1; j <= b; j++)
      for (long int k = 1; k <= c; k++) {
        if (nod[i * j * k] == -1) nod[i * j * k] = func(i * j * k);
        ans = ans + nod[i * j * k];
      }
  cout << ans << endl;
  return 0;
}
