#include <bits/stdc++.h>
using namespace std;
const int MOD = 1073741824;
long long sol[1000001];
long long d(long long a) {
  if (sol[a] != 0) {
    return sol[a];
  }
  int i, c = 0;
  for (i = 1; i <= a / i; i++) {
    if (a % i == 0) {
      if (i * i != a) {
        c++;
      }
      c++;
    }
  }
  sol[a] = c;
  return c;
}
int main() {
  long long a, b, c, m = 0, sum = 0, i, j, v;
  cin >> a >> b >> c;
  for (i = 1; i <= a; i++)
    for (j = 1; j <= b; j++)
      for (v = 1; v <= c; v++) {
        sum += d(i * j * v);
      }
  cout << sum % MOD;
  return 0;
}
