#include <bits/stdc++.h>
using namespace std;
long long int spf[1000050];
void sieve() {
  spf[1] = 1;
  for (long long int i = 2; i < 1000050; i++) spf[i] = i;
  for (long long int i = 4; i < 1000050; i += 2) spf[i] = 2;
  for (long long int i = 3; i * i < 1000050; i++) {
    if (spf[i] == i) {
      for (long long int j = i * i; j < 1000050; j += i)
        if (spf[j] == j) spf[j] = i;
    }
  }
}
long long int countDivisors(long long int x) {
  long long int ans = 1;
  map<long long int, long long int> freq;
  while (x != 1) {
    freq[spf[x]]++;
    x = x / spf[x];
  }
  for (auto x : freq) {
    ans *= (x.second + 1);
  }
  return ans;
}
void solution() {
  long long int a, b, c;
  cin >> a >> b >> c;
  vector<long long int> nos;
  for (long long int i = 1; i <= a; i++) {
    for (long long int j = 1; j <= b; j++) {
      for (long long int k = 1; k <= c; k++) {
        nos.push_back(i * j * k);
      }
    }
  }
  long long int s1 = 0;
  long long int n = nos.size();
  for (long long int i = 0; i < n; i++) {
    s1 += countDivisors(nos[i]) % 1073741824;
  }
  cout << s1 % 1073741824 << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  sieve();
  solution();
  return 0;
}
