#include <bits/stdc++.h>
using namespace std;
int answ[1000005];
int div(int n) {
  if (answ[n] != -1) {
    return answ[n];
  }
  int sqr = (int)sqrt((double)n);
  int ans = 0;
  for (int i = 1; i <= sqr; i++) {
    if (n % i == 0) {
      ans++;
      if (i * i != n) {
        ans++;
      }
    }
  }
  answ[n] = ans;
  return ans;
}
int main() {
  memset(answ, -1, sizeof(answ));
  int a, b, c;
  unsigned long long sum = 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++) {
        sum += div(i * j * k);
        sum %= 1073741824;
      }
    }
  }
  cout << sum % 1073741824 << endl;
  return 0;
}
