#include <bits/stdc++.h>
using namespace std;
long long divisor(long long n) {
  long long cntr = 0;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (n / i == i)
        cntr++;
      else
        cntr += 2;
    }
  }
  return cntr;
}
int main() {
  long long a, b, c, arr[1000005] = {0}, i, j, k;
  cin >> a >> b >> c;
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      for (k = 1; k <= c; k++) {
        arr[i * j * k]++;
      }
    }
  }
  long long ans = 0;
  for (i = 1; i <= a * b * c; i++) {
    if (arr[i] != 0) ans += (divisor(i) * arr[i]);
    ans %= 1073741824;
  }
  cout << ans;
  return 0;
}
