//#define _GLIBCXX_DEBUG

#include<bits/stdc++.h>
using namespace std;

#define endl '\n'
#define lfs cout<<fixed<<setprecision(10)
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = (n); i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = (ll)(m) - 1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template<typename T1, typename T2>bool chmin(T1 &a,T2 b){if(a>b){a=b;return true;}else return false;}
template<typename T1, typename T2>bool chmax(T1 &a,T2 b){if(a<b){a=b;return true;}else return false;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T>void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++){cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>&v,ll h,ll w){for(ll i=0;i<h;i++){for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
template<typename T>void debug(vector<T>&v,ll n){if(n!=0)cout<<v[0];for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
template<typename T>vector<vector<T>>vec(ll x, ll y, T w){vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
vector<ll>dx={1,-1,0,0,1,1,-1,-1};vector<ll>dy={0,0,1,-1,1,-1,1,-1};
template<typename T>vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v(ts...))>(a,make_v(ts...));}
template<typename T1, typename T2>ostream &operator<<(ostream &os, const pair<T1, T2>&p){return os << p.first << " " << p.second;}
template<typename T>ostream &operator<<(ostream &os, const vector<T> &v){for(auto &z:v)os << z << " ";cout<<"|"; return os;}
template<typename T>void rearrange(vector<ll>&ord, vector<T>&v){
  auto tmp = v;
  for(int i=0;i<tmp.size();i++)v[i] = tmp[ord[i]];
}
template<typename Head, typename... Tail>void rearrange(vector<ll>&ord,Head&& head, Tail&&... tail){
  rearrange(ord, head);
  rearrange(ord, tail...);
}
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
int popcount(ll x){return __builtin_popcountll(x);};
int poplow(ll x){return __builtin_ctzll(x);};
int pophigh(ll x){return 63 - __builtin_clzll(x);};
vector<ll> bfs(vector<vector<ll>>&g,ll k=0){
  vector<ll>dist(g.size(),INF);
  queue<P> q;
  ll n=g.size();
  q.emplace(k,0);
  while(!q.empty()){
    ll x=q.front().fi;
    ll len=q.front().se;
    if(dist[x]==INF){
      dist[x]=len;
      for(ll i=0;i<g[x].size();i++){
        q.emplace(g[x][i],len+1);
      }
    }
    q.pop();
  }
  return dist;
}
void check(vector<vector<ll>>g){
  ll n=g.size();
  ll mx=0;
  rep(i,0,n){
    auto d=bfs(g,i);
    rep(j,0,n)chmax(mx,d[j]);
  }
  cout<<mx<<endl;
}
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res=0,buf=0;
  bool judge = true;
  ll n;cin>>n;
  vector<P>v(n);
  vector<vector<ll>>g(n);
  rep(i,1,n+1){
    ll l=(2*(i-1))%n+1;
    ll r=(2*(i-1)+1)%n+1;
    cout<<l spa r<<endl;
    g[i-1].PB(l-1);
    g[i-1].PB(r-1);
  }
  //check(g);
  return 0;
}
#include<bits/stdc++.h>
using namespace std;
 
#define INF 1234567890
#define ll long long

int N;
vector<int> g[2020];
int dist[2020];

int main()
{
	scanf("%d", &N);
	for(int i=0; i<N/2; i++)
	{
		g[i].push_back(i*2);
		g[i].push_back(i*2+1);
	}
	for(int i=N/2; i<N; i++)
	{
		g[i].push_back((i*2)%N);
		g[i].push_back((i*2+1)%N);
	}

	// int mx = 0;
	// for(int i=0; i<N; i++)
	// {
	// 	memset(dist, 0x3f, sizeof(dist));
	// 	queue<int> q;
	// 	q.push(i); dist[i] = 0;
	// 	while(!q.empty())
	// 	{
	// 		int n = q.front(); q.pop();
	// 		for(int next : g[n])
	// 		{
	// 			if (dist[next] != 0x3f3f3f3f) continue;
	// 			q.push(next); dist[next] = dist[n] + 1;
	// 		}
	// 	}
	// 	for(int j=0; j<N; j++)
	// 	{
	// 		//if (dist[j] > 10) printf("D[%d][%d] = %d\n", i, j, dist[j]);
	// 		mx = max(mx, dist[j]);
	// 	}
	// }
	// printf("mx : %d\n", mx);

	for(int i=0; i<N; i++)
		printf("%d %d\n", g[i][0]+1, g[i][1]+1);
	return 0;
}