#include<iostream>
#include<cstdio>
#define N 250000
using namespace std;
int read()
{
    char c=0;
    int sum=0;
    while (c<'0'||c>'9') c=getchar();
    while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
    return sum;
}
struct reads
{
    int x,y;
};
reads tong[N+1];
int n,length,cnt;
int main()
{
    n=read();
    if (n&1)
    {
	for (int i=1;i<=((n+1)>>1);++i)
	{
	    for (int j=1;j<=(n>>1);++j) tong[++length]=(reads){i,(i-1+j)%n+1};
	    if (i!=((n+1)>>1))
	    {
		for (int j=1;j<=(n>>1);++j) tong[++length]=(reads){(i+((n+1)>>1)-1)%n+1,(i+((n+1)>>1)-1+j)%n+1};
	    }
	}
    }
    else
    {
	n--;
	for (int i=1;i<=((n+1)>>1);++i)
	{
	    for (int j=1;j<=(n>>1);++j) tong[++length]=(reads){i,(i-1+j)%n+1};
	    tong[++length]=(reads){i%n+1,n+1};
	    if (i!=((n+1)>>1))
	    {
		for (int j=1;j<=(n>>1);++j) tong[++length]=(reads){(i+((n+1)>>1)-1)%n+1,(i+((n+1)>>1)-1+j)%n+1},++cnt;
		tong[++length]=(reads){(i+((n+1)>>1))%n+1,n+1};
	    }
	}
    }
    for (int i=1;i<=length;++i) printf("%d %d\n",min(tong[i].x,tong[i].y),max(tong[i].x,tong[i].y));
    return 0;
}