#include <bits/stdc++.h>
using namespace std;
bool iss(int d) {
  for (int i = 2; i * i <= d; ++i)
    if (d % i == 0) return false;
  return true;
}
int main() {
  int a, b, c;
  scanf("%d%d%d", &a, &b, &c);
  vector<int> simple;
  for (int i = 2; i < 100; ++i)
    if (iss(i)) simple.push_back(i);
  vector<vector<int> > d(101);
  for (int i = 1; i <= 100; ++i) {
    d[i].resize(simple.size());
    for (int j = 0, tmp = i; j < simple.size(); ++j)
      while (tmp % simple[j] == 0) {
        tmp /= simple[j];
        d[i][j]++;
      }
  }
  int ans = 0;
  int mod = 1 << 30;
  for (int i = 1; i <= a; ++i)
    for (int j = 1; j <= b; ++j)
      for (int k = 1; k <= c; ++k) {
        int prod = 1;
        for (int l = 0; l < simple.size(); ++l)
          prod *= d[i][l] + d[j][l] + d[k][l] + 1;
        ans = (ans + prod) % mod;
      }
  printf("%d\n", ans);
  return 0;
}
