#include <bits/stdc++.h>
using namespace std;
long long a, b, c, sum;
long long primos[100], cp;
void Criba() {
  for (long long i = 2; i < 100; i++) {
    bool esprimo = true;
    for (long long j = 2; j * j <= i; j++)
      if (i % j == 0) {
        esprimo = false;
      }
    if (esprimo) primos[cp++] = i;
  }
}
long long Div(long long n) {
  long long resp = 1, c;
  for (int i = 0; i < cp; i++) {
    c = 0;
    while (n % primos[i] == 0) {
      n /= primos[i];
      c++;
    }
    resp *= c + 1;
    resp %= 1073741824;
  }
  return resp;
}
int main() {
  Criba();
  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;
  return 0;
}
