#include <bits/stdc++.h>
using namespace std;
const int N = 4000000;
int a, b, c, n, cnt;
int prime[N], flg[N + 10], mu[N + 10];
int fs[N + 10], gs[N + 10], cs[N + 10], f[N + 10];
void getPrime() {
  mu[1] = 1;
  for (int i = 2; i <= n; i++) {
    if (!flg[i]) mu[i] = -1, prime[++cnt] = i;
    for (int j = 1; j <= cnt && i * prime[j] <= n; j++) {
      flg[i * prime[j]] = 1;
      if (i % prime[j] == 0) {
        mu[i * prime[j]] = 0;
        break;
      }
      mu[i * prime[j]] = -mu[i];
    }
  }
}
int main() {
  scanf("%d%d%d", &a, &b, &c);
  if (b < a) a ^= b ^= a ^= b;
  if (c < b) b ^= c ^= b ^= c;
  n = a * b;
  getPrime();
  for (int i = 1; i <= a; i++)
    for (int j = 1; j <= b; j++) f[i * j]++;
  for (int i = 1; i <= n; i++)
    for (int j = i; j <= n; j += i) fs[i] += f[j];
  for (int i = 1; i <= n; i++)
    for (int j = i; j <= n; j += i) cs[i] += c / j;
  for (int i = 1; i <= n; i++)
    for (int j = i; j <= n; j += i) gs[j] += cs[i] * mu[i];
  int res = 0;
  for (int i = 1; i <= n; i++) res += fs[i] * gs[i];
  printf("%d\n", res & (1 << 30) - 1);
  return 0;
}
