#include <bits/stdc++.h>
using namespace std;
bool p[1000001];
vector<int> v;
void sieve() {
  memset(p, true, sizeof(p));
  for (int i = 2; i <= sqrt(1000001); i++) {
    if (p[i] == true) {
      for (int j = i * 2; j <= 1000001; j += i) p[j] = false;
    }
  }
  for (int i = 2; i <= 1000000; i++) {
    if (p[i] == true) v.push_back(i);
  }
}
int main() {
  sieve();
  int a, b, c;
  cin >> a >> b >> c;
  long long int ans = 0;
  for (int i = 1; i <= a; i++) {
    for (int j = 1; j <= b; j++) {
      for (int k = 1; k <= c; k++) {
        int sum = (i * j * k);
        if (sum == 1)
          ans += 1;
        else if (p[sum] == true)
          ans += 2;
        else {
          long long int mul = 1;
          for (int l = 0; v[l] <= sum; l++) {
            int count = 0;
            while (sum % v[l] == 0) {
              sum /= v[l];
              count++;
              if (sum == 1) break;
            }
            if (count != 0) mul *= ((count + 1) % 1073741824);
          }
          ans += (mul) % 1073741824;
        }
      }
    }
  }
  cout << ans << endl;
}
