#include <bits/stdc++.h>
using namespace std;
int n;
int rev(int x) {
	if(x <= 0) return x + n;
	if(x > n) return x - n;
	return x;
}
int main() {
	scanf("%d", &n);
	if(n & 1) {
		for(int i = 1;i <= n;i++) {
			for(int j = 1;j <= n / 2;j++) {
				int u = rev(i - j + 1), v = rev(i + j);
				if(u > v) swap(u, v);
				printf("%d %d\n", u, v);
			}
		}
	}
	else {
		int cnt = 0, now = 0;
		n --;
		for(int i = 1;i <= n;i++) {
			for(int j = 1;j <= n / 2;j++) {
				int u = rev(i - j + 1), v = rev(i + j);
				cnt ++;
				if(u > v) swap(u, v);
				printf("%d %d\n", u, v);
				if(cnt == n - 1) cnt = 0, now ++, printf("%d %d\n", now, n + 1);
			}
		}
	}
}