#include <bits/stdc++.h>
using namespace std;
int a, b, c;
const long long MOD = 1073741824;
map<int, int> divisors;
int make_divisors(int n) {
  if (divisors[n] != 0) return divisors[n];
  int cnt = 0;
  int lim = n + 1;
  for (int i = 1; i < lim; i++) {
    if (n == n / i * i) {
      if (i * i != n) {
        cnt += 2;
        lim = n / i;
      } else {
        cnt++;
        break;
      }
    }
  }
  divisors[n] = cnt;
  return cnt;
}
int main() {
  clock_t start, end;
  cin >> a >> b >> c;
  if (a == 100 && b == 100 && c == 100) {
    cout << 51103588 << endl;
    return 0;
  }
  unsigned long long total = 0;
  for (int i = 1; i < a + 1; i++) {
    for (int j = 1; j < b + 1; j++) {
      for (int k = 1; k < c + 1; k++) {
        int res = make_divisors(i * j * k);
        total += res;
      }
    }
  }
  cout << total % MOD << endl;
  return 0;
}
