#pragma GCC optimize("O3")
#include <bits/stdc++.h>
 
using namespace std;
typedef long long ll;
 
int n;
 
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
 
    ifstream cin("lacate.in");
    ofstream cout("lacate.out");
 
    cin >> n;
    cout << n << " " << n << "\n";
    for (int i = 1; i < n; i++) {
        cout << i << " " << i + 1 << "\n";
    }
    cout << 1 << " " << n;
    
	return 0;
}