#include <bits/stdc++.h>
using namespace std;
template <typename T>
ostream& operator<<(ostream& os, vector<T>& v) {
  for (auto element : v) {
    os << element << " ";
  }
  return os;
}
template <typename T, typename second>
ostream& operator<<(ostream& os, pair<T, second>& p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, set<T>& v) {
  auto endit = v.end();
  endit--;
  os << "[";
  for (auto it = v.begin(); it != v.end(); it++) {
    os << *it;
    if (it != endit) {
      os << ", ";
    }
  }
  os << "]";
  return os;
}
template <typename T, typename second>
ostream& operator<<(ostream& os, map<T, second>& v) {
  auto endit = v.end();
  endit--;
  os << "{";
  for (auto it = v.begin(); it != v.end(); it++) {
    os << "(" << (*it).first << " : " << (*it).second << ")";
    if (it != endit) {
      os << ", ";
    }
  }
  os << "}";
  return os;
}
bool isPrime(long long n) {
  long long num = n;
  for (long long i = 2; i * i <= num; i++) {
    if (num % i == 0) return false;
  }
  return true;
}
void solve() {
  long long n;
  cin >> n;
  if (n == 2)
    cout << "1";
  else if (isPrime(n))
    cout << "1";
  else if (n % 2 == 0)
    cout << "2";
  else {
    if (isPrime(n - 2))
      cout << "2";
    else
      cout << "3";
  }
  cout << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  for (long long i = 0; i < t; i++) solve();
  return 0;
}
