#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define piii tuple<int,int,int>
#define mp make_pair
#define mt make_tuple
#define x first
#define y second
#define fi first
#define se second
#define ins insert
#define it iterator
#define lb lower_bound
#define ub upper_bound
#define exc(exp) if(exp)continue;
#define ret(exp) if(exp)return;
#define stop(exp) if(exp)break;
#define quit(sth) {sth;return;}
#define let(var...) int var;tie(var)
#define siz(vec) ((int)((vec).size()))
#define all(vec) (vec).begin(),(vec).end()
#define unq(vec) sort(all(vec)),(vec).erase(unique(all(vec)),(vec).end())
#define deb(var) cerr<<#var<<'='<<(var)<<"; "
#define debl(var) cerr<<#var<<'='<<(var)<<";\n"
#define db double
#define ll long long
#define int long long
#define inf (long long)(1e18)
mt19937 gen(random_device{}());
bool Max(int &x,int y){if(x<y)return x=y,1;return 0;}
bool Min(int &x,int y){if(x>y)return x=y,1;return 0;}
const int mod=1e9+7;
void Add(int &x,int y){x=x+y<mod?x+y:x+y-mod;}
int add(int x,int y){return x+y<mod?x+y:x+y-mod;}
int fpm(int x,int y){
	int ans=1;for(;y;y>>=1,(x*=x)%=mod)if(y&1)(ans*=x)%=mod;return ans;
}

int n,kx,bx,ky,by,fl;
vector<pii> Ans;
void Put(int x,int y){
    if(fl)fl=0;else Ans.pb({kx*x+bx,ky*y+by});
}
void sol1(int n){
    if(n==1)quit(Put(1,1));
    for(int i=n;i>=3;i-=2)
        Put(1,i),Put(i-1,1),
        Put(i,1),Put(1,i-1);
    Put(2,2);
    for(int i=3;i<=n-2;i+=2)
        Put(2,i),Put(i+1,2),
        Put(i,2),Put(2,i+1);
    Put(2,n);
    Put(n,n);Put(1,1),Put(n,2);
    fl=1,bx+=kx*(n+1),kx=-kx,by+=2*ky;sol1(n-2);
}
vector<pii> sol2(int n){
    sol1(n-1);
    auto ans=Ans;
    for(auto &t:ans)++t.x,++t.y;
    let(x,y)=ans.back();ans.pop_back();
    assert(x!=y);
    ans.pb({1,y}),ans.pb({x,1}),ans.pb({x,y});
    vector<int> free(0);
    for(int i=2;i<=n;i++)
        if(i!=x&&i!=y)free.pb(i);
    assert(siz(free)&1);
    for(int i=0;i+1<siz(free);i+=2){
        ans.pb({1,free[i]}),ans.pb({free[i+1],1}),
        ans.pb({free[i],1}),ans.pb({1,free[i+1]});
    }
    ans.pb({1,free.back()}),ans.pb({1,1}),ans.pb({free.back(),1});return ans;
}
void work(){
    kx=ky=1;
    cin>>n;
    if(n==2)cout<<"1\n1 1\n";
    else if(n&1){
        cout<<n*n<<'\n';
        sol1(n);
        for(auto t:Ans)cout<<t.x<<' '<<t.y<<'\n';
    }else{
        cout<<n*n-2<<'\n';
        auto ans=sol2(n);
        for(auto t:ans)cout<<t.x<<' '<<t.y<<'\n';
    }
}
signed main(){
	ios::sync_with_stdio(0),
	cin.tie(0),cout.tie(0);
	int T=1;while(T--)work();
}
/*
 * CONTINUE, NON-STOPPING, FOR THE FAITH
 * START TYPING IF YOU DON'T KNOW WHAT TO DO
 * STOP TYPING IF YOU DON'T KNOW WHAT YOU'RE DOING
 */