#include <bits/stdc++.h>
#define SZ(x) (int) x.size() - 1
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> void chkmax(T &x, T y) { x = max(x, y); }
template <typename T> void chkmin(T &x, T y) { x = min(x, y); }
template <typename T> void read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = x * 10 + c - '0';
	x *= f;
}
int n;
int calc(int x) {
	return (x + n - 1) % n + 1;
}
void work(int x, int y) {
	x = calc(x), y = calc(y);
	cout << min(x, y) << " " << max(x, y) << endl;
}
signed main() {
	cin >> n;
	if (n & 1) {
		int k = n / 2;
		F(i, 1, n) {
			F(j, 1, k) work(i - j + 1, i + j);
		}
		return 0;
	}
	n--;
	int k = n / 2;
	F(i, 1, n) {
		F(j, 1, k) work(i - j + 1, i + j);
		cout << calc(i + k + 1) << " " << n + 1 << endl;
	}
	return 0;
}