#include <bits/stdc++.h>
using namespace std;
const int MOD = 1073741824;
const int N = 100005;
const double PI = 4 * atan(1);
int dx[] = {1, -1, 0, 0, 1, -1, 1, -1};
int dy[] = {0, 0, 1, -1, 1, 1, -1, -1};
long long gcd(long long a, long long b) { return (b == 0 ? a : gcd(b, a % b)); }
long long lcm(long long a, long long b) { return a * (b / gcd(a, b)); }
bool issquare(long long w) { return trunc(sqrt(w)) * trunc(sqrt(w)) == w; }
bool isprime(long long u) {
  for (long long i = 2; i <= (int)sqrt(u); i++) {
    if (u % i == 0) return 0;
  }
  return 1;
}
long long mod(long long to_mod) {
  to_mod %= MOD;
  while (to_mod < 0) to_mod += MOD;
  return to_mod % MOD;
}
long long moduloMultiplication(long long a, long long b, long long mod) {
  long long res = 0;
  a %= mod;
  while (b) {
    if (b & 1) res = (res + a) % mod;
    a = (2 * a) % mod;
    b >>= 1;
  }
  return res;
}
long long power(long long x, long long y) {
  long long res = 1;
  x = x;
  while (y > 0) {
    if (y & 1) res = (res * x);
    y = y >> 1;
    x = (x * x);
  }
  return res;
}
long long _sieve_size;
bitset<1000010> bs;
vector<long long> primes;
void sieve(long long upperbound) {
  _sieve_size = upperbound + 1;
  bs.set();
  bs[0] = bs[1] = 0;
  for (long long i = 2; i <= _sieve_size; i++)
    if (bs[i]) {
      for (long long j = i * i; j <= _sieve_size; j += i) bs[j] = 0;
      primes.push_back(i);
    }
}
long long numDiv(long long N) {
  long long PF_idx = 0, PF = primes[PF_idx], ans = 1;
  while (PF * PF <= N) {
    long long power = 0;
    while (N % PF == 0) {
      N /= PF;
      power++;
    }
    ans *= (power + 1);
    PF = primes[++PF_idx];
  }
  if (N != 1) ans *= 2;
  return ans;
}
int main() {
  sieve(1000000);
  long long t[1000005];
  for (int i = 1; i <= 1000000; i++) {
    t[i] = numDiv(i);
  }
  long long a, b, c, ans = 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++) {
        ans = mod(ans + t[i * j * k]);
      }
    }
  }
  cout << ans;
  return 0;
}
