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