#include <bits/stdc++.h>
using namespace std;
unsigned long long binpow(unsigned long long a, unsigned long long n) {
  if (n == 0) return 1;
  if (n % 2 == 1) {
    unsigned long long cur_1 = binpow(a, n - 1);
    unsigned long long cur_2 =
        ((cur_1 % 1073741824) * (a % 1073741824)) % 1073741824;
    return cur_2;
  } else {
    unsigned long long b = binpow(a, n / 2);
    unsigned long long cur_3 =
        ((b % 1073741824) * (b % 1073741824)) % 1073741824;
    return cur_3;
  }
}
int main() {
  long result[1000000] = {0};
  long i, j, p, t, n;
  for (i = 0; i < 1000000; i++) {
    p = i + 1;
    for (j = p; j <= 1000000; j += p) {
      result[j - 1]++;
    }
  }
  int a, b, c;
  cin >> a >> b >> c;
  unsigned long long count = 0;
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int k = 1; k <= c; k++) {
        count += result[i * j * k - 1];
        count %= 1073741824;
      }
    }
  }
  cout << count;
  return 0;
}
