#include <bits/stdc++.h>
using namespace std;
const int MOD = 1 << 30;
int a, b, c, ans, i, j, z;
int sieve[1 << 20];
int least_div[1 << 20];
int d(int p) {
  int ans = 1, cnt = 0, curr;
  while (p > 1) {
    curr = least_div[p];
    while (least_div[p] == curr) {
      cnt++;
      p /= curr;
    }
    ans *= (cnt + 1);
    cnt = 0;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  for (i = 2; i * i <= 1000000; i++) {
    if (!sieve[i]) {
      least_div[i] = i;
      for (j = i * i; j <= 1000000; j += i) {
        if (!sieve[j]) {
          sieve[j] = true;
          least_div[j] = i;
        }
      }
    }
  }
  cin >> a >> b >> c;
  for (i = 1; i <= a; i++)
    for (j = 1; j <= b; j++)
      for (z = 1; z <= c; z++) ans = (ans + d(i * j * z)) % MOD;
  cout << ans << '\n';
}
