#include <bits/stdc++.h>
#define For(i,a,b) for(int i=a;i<=b;i++)
#define Rev(i,a,b) for(int i=a;i>=b;i--)
#define Fin(file) freopen(file,"r",stdin)
#define Fout(file) freopen(file,"w",stdout)
using namespace std; using ll = long long;
const int N=505;
int n;
void Solve1(){
	For(i,0,n-1){
		For(j,1,n/2) cout<<1+(i-j+n)%n<<' '<<1+(i+j)%n<<'\n';
	}
}
void Solve2(){
	For(i,0,n-2){
		For(j,1,n/2-1) cout<<1+(i-j+n-1)%(n-1)<<' '<<1+(i+j)%(n-1)<<'\n';
		cout<<1+i<<' '<<1+n-1<<'\n';
	}
}
int main(){
	cin>>n; if(n%2==1) Solve1(); else Solve2();
	return 0;
}