#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T checkbit(T n, T i) {
  T n_ = n;
  return ((n_ >> i) & T(1));
}
template <typename T>
inline T bitcount(T n) {
  T n_ = n;
  return __builtin_popcount(n_);
}
template <typename T>
inline T isPowerOfTwo(T n) {
  T n_ = n;
  return (n_ != 0 and ((n_ & (n_ - 1)) == 0));
}
template <typename T>
inline T sqr(T x) {
  T x_ = (x);
  return x_ * x_;
}
template <typename T>
inline T qbr(T x) {
  T x_ = (x);
  return ((x_ * x_) * x_);
}
template <typename T>
inline int sign(T x) {
  T x_ = (x);
  return ((x_ > T(0)) - (x_ < T(0)));
}
template <typename T>
inline T mod(T x, T m) {
  T x_ = (x);
  return (((x_) >= 0) ? ((x_) % (m)) : ((((x_) % (m)) + (m)) % (m)));
}
template <typename T>
inline T gcd(T a, T b) {
  while (b) {
    T t = a % b;
    a = b;
    b = t;
  }
  return a;
}
template <typename T>
inline T gcd_ex(T a, T b, T& x, T& y) {
  if (b == 0) {
    x = 1, y = 0;
    return a;
  }
  T x1, y1;
  T d = gcd_ex(b, a % b, x1, y1);
  x = y1;
  y = x1 - (a / b) * y1;
  return d;
}
template <typename T>
inline T lcm(T a, T b) {
  return (a * (b / gcd(a, b)));
}
template <typename T>
inline T binpow(T x, T deg) {
  T res = (T)1;
  for (; deg; x *= x, deg >>= 1)
    if (deg & 1) res *= x;
  return res;
}
template <typename T>
inline T modpow(T x, T deg, T m) {
  assert(deg >= (T)0);
  T res = (T)(1);
  for (; deg; x = mod(mod(x, m) * mod(x, m), m), deg >>= 1)
    if (deg & 1) res = mod(mod(res, m) * mod(x, m), m);
  return res;
}
template <typename Collection, typename UnaryOperation>
void foreach (Collection& col, UnaryOperation op) {
  for_each(begin(col), end(col), op);
}
template <typename Collection, typename UnaryOperation>
Collection fmap(Collection& col, UnaryOperation op) {
  transform(begin(col), end(col), col.begin(), op);
  return col;
}
template <typename Collection, typename binop>
Collection zip(Collection& fc, Collection& sc, binop op) {
  transform(begin(fc), end(fc), sc.begin(), fc.begin(), op);
  return fc;
}
template <typename Collection, typename Condition>
bool exists(Collection& col, Condition con) {
  auto exist = find_if(begin(col), end(col), con);
  return exist != col.end();
}
template <typename Collection, typename Predicate>
Collection filterNot(Collection& col, Predicate predicate) {
  auto returnIterator = remove_if(begin(col), end(col), predicate);
  col.erase(returnIterator, end(col));
  return col;
}
template <class T1, class T2>
istream& operator>>(istream& in, pair<T1, T2>& P) {
  in >> P.first >> P.second;
  return in;
}
template <class T>
istream& operator>>(istream& in, vector<T>& Col) {
  for (auto& el : Col) in >> el;
  return in;
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
  for (auto& row : v) {
    for (auto& el : row) os << el << " ";
    os << "\n";
  }
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const map<T1, T2>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <typename First>
void read(First& t) {
  cin >> t;
}
template <typename First, typename... Args>
void read(First& f, Args&... args) {
  cin >> f;
  read(forward<Args&>(args)...);
}
template <typename T>
void print(T&& t) {
  cout << t << endl;
}
template <typename First, typename... Args>
void print(First&& f, Args&&... args) {
  cout << f << " ";
  print(forward<Args&&>(args)...);
}
template <typename T>
void printLn(T&& t) {
  cout << t << endl;
}
template <typename First, typename... Args>
void printLn(First&& f, Args&&... args) {
  cout << f << endl;
  printLn(forward<Args&&>(args)...);
}
template <typename T, size_t N>
struct MakeTensor {
  template <typename... Args>
  static auto make_tensor(size_t first, Args... sizes)
      -> vector<decltype(MakeTensor<T, N - 1>::make_tensor(sizes...))> {
    auto inner = MakeTensor<T, N - 1>::make_tensor(sizes...);
    return vector<decltype(inner)>(first, inner);
  }
};
template <typename T>
struct MakeTensor<T, 1> {
  static vector<T> make_tensor(size_t size) { return vector<T>(size); }
};
template <typename T, typename... Args>
auto make_tensor(Args... args)
    -> decltype(MakeTensor<T, sizeof...(Args)>::make_tensor(args...)) {
  return MakeTensor<T, sizeof...(Args)>::make_tensor(args...);
}
int main() {
  long long n;
  cin >> n;
  cout << sqr(n - 2) << endl;
  return 0;
}
