#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  long long int count = 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++) {
        long long int m = 1, n = i * j * k;
        for (long long int l = 2; l <= n; l++) {
          int c = 0;
          while (n % l == 0) {
            c++;
            n /= l;
          }
          m *= (c + 1);
        }
        count += m;
      }
  cout << count % 1073741824;
  return 0;
}
