#include <bits/stdc++.h>
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
using datas = pair<ll, ll>;
using ddatas = pair<long double, long double>;
using tdata = pair<ll, datas>;
using vec = vector<ll>;
using mat = vector<vec>;
using pvec = vector<datas>;
using pmat = vector<pvec>;
const ll mod = 1000000007;
const ll inf = 1LL << 60;
const long double PI = acos(-1);
const long double eps = 1e-9;
template <class T>
inline bool chmax(T& a, T b) {
  bool x = a < b;
  if (x) a = b;
  return x;
}
template <class T>
inline bool chmin(T& a, T b) {
  bool x = a > b;
  if (x) a = b;
  return x;
}
void startupcpp() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}
long double distance(ddatas x, ddatas y) {
  long double a = x.first - y.first, b = x.second - y.second;
  return sqrt(a * a + b * b);
}
ll modinv(ll a) {
  ll b = mod, u = 1, v = 0, t;
  while (b) {
    t = a / b;
    a -= t * b;
    swap(a, b);
    u -= t * v;
    swap(u, v);
  }
  return (u + mod) % mod;
}
ll moddevide(ll a, ll b) { return (a * modinv(b)) % mod; }
vec modncrlistp, modncrlistm;
ll modncr(ll n, ll r) {
  if (n < r) return 0;
  ll i, size = modncrlistp.size();
  if (size <= n) {
    modncrlistp.resize(n + 1);
    modncrlistm.resize(n + 1);
    if (!size) {
      modncrlistp[0] = modncrlistm[0] = 1;
      size++;
    }
    for (i = size; i < (ll)n + 1; ++i) {
      modncrlistp[i] = modncrlistp[i - 1] * i % mod;
      modncrlistm[i] = modinv(modncrlistp[i]);
    }
  }
  return modncrlistp[n] * modncrlistm[r] % mod * modncrlistm[n - r] % mod;
}
ll modpow(ll a, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1) res = res * a % mod;
    a = a * a % mod;
    n >>= 1;
  }
  return res;
}
ll gcd(ll a, ll b) {
  if (!b) return abs(a);
  return (a % b == 0) ? abs(b) : gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
ll countdigits(ll n) {
  ll ans = 0;
  while (n) {
    n /= 10;
    ans++;
  }
  return ans;
}
ll sumdigits(ll n) {
  ll ans = 0;
  while (n) {
    ans += n % 10;
    n /= 10;
  }
  return ans;
}
void topcoder(vector<int>& v) {
  string s;
  while (1) {
    cin >> s;
    int i = s[0] == '{', x = 0;
    while (s[i] >= '0' && s[i] <= '9') {
      x = x * 10 + s[i] - '0';
      ++i;
    }
    v.emplace_back(x);
    if (s[i] == '}') break;
  }
}
void topcoder(string& s) {
  string t;
  cin >> t;
  int i = 1;
  while (t[i] != '"') {
    s += t[i++];
  }
}
ll N, M, K, H, W, A, B, C, D;
int main() {
  startupcpp();
  ll i, j;
  cin >> N;
  vec ansa = {-2, -1, 0, -2, 0, -2, -1, 0}, ansb = {0, 0, 0, 1, 1, 2, 2, 2};
  for (i = 0; i < (ll)N; ++i) {
    if (i & 1) {
      ansa.emplace_back(i * 2 + 1);
      ansa.emplace_back(i * 2 + 2);
      ansa.emplace_back(i * 2);
      ansa.emplace_back(i * 2 + 2);
      ansa.emplace_back(i * 2);
      ansa.emplace_back(i * 2 + 1);
      ansa.emplace_back(i * 2 + 2);
      ansb.emplace_back(2);
      ansb.emplace_back(2);
      ansb.emplace_back(1);
      ansb.emplace_back(1);
      ansb.emplace_back(0);
      ansb.emplace_back(0);
      ansb.emplace_back(0);
    } else {
      ansa.emplace_back(i * 2 + 1);
      ansa.emplace_back(i * 2 + 2);
      ansa.emplace_back(i * 2);
      ansa.emplace_back(i * 2 + 2);
      ansa.emplace_back(i * 2);
      ansa.emplace_back(i * 2 + 1);
      ansa.emplace_back(i * 2 + 2);
      ansb.emplace_back(2);
      ansb.emplace_back(2);
      ansb.emplace_back(3);
      ansb.emplace_back(3);
      ansb.emplace_back(4);
      ansb.emplace_back(4);
      ansb.emplace_back(4);
    }
  }
  cout << ansa.size() << "\n";
  for (i = 0; i < (ll)ansa.size(); ++i) {
    cout << ansa[i] << " " << ansb[i] << "\n";
  }
}
