#include <bits/stdc++.h>
using namespace std;
const long long N = 1e7, OO = 1e14;
const int di[] = {1, -1, 0, 0};
const int dj[] = {0, 0, 1, -1};
long long TC, n, m, k, a, b, c, cnt, sum, mx, mn, ans, arr[N];
bool f, vis[N], mark[N];
int solve(int x) {
  int cnt = 0, i = 1;
  for (; i * i < x; i++)
    if (x % i == 0) cnt += 2;
  if (i * i == x) cnt++;
  return cnt;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(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++) {
        m = i * j * k;
        ans += solve(m);
      }
    }
  }
  cout << ans % 1073741824;
  return 0;
}
