#include <bits/stdc++.h>
using namespace std;
const int maxN = 1e6, M = 1073741824;
long long d[maxN + 1];
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  for (int i = 1; i <= maxN; ++i) {
    for (int j = i; j <= maxN; j += i) {
      d[j]++;
    }
  }
  int a, b, c;
  cin >> a >> b >> c;
  int ans = 0;
  for (int i = 1; i <= a; ++i) {
    for (int j = 1; j <= b; ++j) {
      for (int k = 1; k <= c; ++k) {
        ans = (ans + d[i * j * k]) % M;
      }
    }
  }
  cout << ans;
}
