#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int a, b, c;
  cin >> a >> b >> c;
  int arr[1000001] = {0};
  long long sum = 0;
  for (long long i = 1; i <= 1000000; i++) {
    for (long long j = i; j <= 1000000; j += i) {
      arr[j]++;
    }
  }
  for (long long i = 1; i <= a; i++) {
    for (long long j = 1; j <= b; j++) {
      for (long long k = 1; k <= c; k++) {
        sum += arr[i * j * k] % 1073741824;
      }
    }
  }
  cout << sum;
  return 0;
}
