#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define mp make_pair
#define si(x) int(x.size())
const int mod=998244353,MAX=300005,INF=1<<30;

int main(){
    
    std::ifstream in("text.txt");
    std::cin.rdbuf(in.rdbuf());
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    vector<pair<int,int>> E;
    for(int i=0;i<20000;i++){
        E.push_back(mp(0,6*i+1));
        E.push_back(mp(6*i+1,6*i+2));
        E.push_back(mp(6*i+2,6*i+3));
        E.push_back(mp(6*i+3,6*i+4));
        E.push_back(mp(6*i+2,6*i+5));
        E.push_back(mp(6*i+5,6*i+6));
    }
    cout<<si(E)+1<<"\n";
    for(auto [a,b]:E) cout<<a+1<<" "<<b+1<<"\n";
}