#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,b) for(int i=0;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rep1(i,b) for(int i=1;i<b;i++)
#define repx(i,x,b) for(int i=x;i<b;i++)
#define fore(i,a) for(auto i:a)
#define fore1(i,a) for(auto &i:a)
#define rng(x) (x).begin(), (x).end()
#define rrng(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define fi first
#define se second

using namespace std;
using namespace atcoder;

using ll = long long;
template<typename T> using mpq = priority_queue<T, vector<T>, greater<T>>;
template<typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> ll sumv(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
bool yn(bool a) { if(a) {cout << "Yes" << endl; return 1;} else {cout << "No" << endl; return 0;}}
#define dame { cout << "No" << endl; return 0;}
#define dame1 { cout << -1 << endl; return 0;}
#define test(x) cout << "test" << x << endl;
#define deb(x,y) cout << x << " " << y << endl;
#define deb3(x,y,z) cout << x << " " << y << " " << z << endl;
#define deb4(x,y,z,x2) cout << x << " " << y << " " << z << " " << x2 << endl;
#define out cout << ans << endl;
#define outv fore(yans , ans) cout << yans << "\n";
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define showv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define showv2(v) fore(vy , v) cout << vy << "\n";
using pll = pair<ll,ll>;
using pil = pair<int,ll>;
using pli = pair<ll,int>;
using pii = pair<int,int>;
using tp = tuple<int ,int ,int>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vb = vector<bool>;
using vpii = vector<pii>;
using vpli = vector<pli>;
using vpll = vector<pll>;
using vpil = vector<pil>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pii>>;
using vvpli = vector<vector<pli>>;
using vvpll = vector<vpll>;
using vvpil = vector<vpil>;
using mint = modint998244353;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
vector<int> dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1};
ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;

struct math_lib{
    vvl div,mul;

    void div_init(int n){
        div.resize(n+1);
        mul.resize(n+1);

        for(ll i = 1;i <= n;i++){
            for(ll j = i;j <= n;j+=i){
                div[j].pb(i);
                mul[i].pb(j);
            }
        }

        return;
    }

    vl divisor(ll x){
        vl res;
        for(ll i=1;i*i<=x;i++){
            if (x%i != 0) continue;
            res.pb(i);
            if (i*i != x) res.pb(x/i); 
        }
        sort(rng(res));
    
        return res;
    }

    ll sqrt(ll x) {
        ll l = 0, r = ll(2e9)+1;
        while (l+1<r) {
          ll c = (l+r)/2;
          if (c*c <= x) l = c; else r = c;
        }
        return l;
    }

    ll logx(ll x,int a){
        ll tmp=1;
        ll ret=0;

        while(tmp <= x){
            if (tmp >= LLONG_MAX/a) break;
            tmp *= a;
            ret++;
        }
        ret--;

        return ret;
    }

    ll pow(ll x , ll a){

        assert(x > 0);
        assert(a >= 0);

        ll ret = 1;

        rep(_,a){
            assert (ret < LLONG_MAX/x);
            ret *= x;
        }

        return ret;
    }

    ll base(ll x,int a){
        ll ans=0,y;
        for (ll i=0;x>0;i++){
            y = x/a;
            ans += (x - y*a)*pow(10,i);
            x = y;
        }
        return ans;
    }

    string baseS(ll x,int a){
        string ans;
        ll y;
        for (ll i=0;x>0;i++){
            y = x/a;
            ans += '0' + (x - y*a);
            x = y;
        }
        reverse(rng(ans));
        return ans;
    }
} math;

// .div.mul : div[i]、mul[i]はそれぞれiの約数、倍数を格納している。
// .div_init(n) : div,mulを初期化。引数はnまで。n < 1e6 ~ 1e7。
// .divisor(x) : xの約数列挙。xは64bit整数。
// .sqrt(x) : floor(sqrt(x))。xは64bit整数。誤差は発生しない。
// .logx(x , a) : floor(loga(x))。xは64bit整数。誤差は発生しない。
// .pow(x , a) : x^a。誤差は発生しない。
// .base(x , a) : x(10進数)をa進数表記に。1 <= a <= 10。戻り値はll型。 
// .baseS(x , a) : x(10進数)をa進数表記に。1 <= a <= 10。戻り値はstring型。 

 
int main(){

    ll n; cin>>n;

    int k = math.logx(n , 2);

    int e =3*k + 2;

    int st = 1;
    int go = 3*k + 2;

    vpii ans;

    rep(i,k){
        int v1,v2;
        v1 = i*2 + 2;
        v2 = i*2 + 3;

        if (i == 0){
            ans.pb({st , v1});
            ans.pb({st , v2});
        }else{
            ans.pb({v1-2 , v1});
            ans.pb({v2-2 , v1});
            ans.pb({v1-2 , v2});
            ans.pb({v2-2 , v2});
        }

        if (i == k-1){
            ans.pb({go , v1});
            ans.pb({go , v2});
        }
    }

    rep1(i,k) ans.pb({2*k + i+2 , 2*k + i+1});

    if (n%2 == 1) ans.pb({2*k + 2 , st});
    ans.pb({3*k + 1 , go});

    rep(i,k-1){
        if ((n >> (i+1) & 1) == 1){
            ans.pb({2*k + i+3 , 2*i + 3});
            ans.pb({2*k + i+3 , 2*i + 2});
        }
    }

    deb(e , sz(ans));

    fore(y , ans) deb(y.fi , y.se);

    


    

    return 0;
}