#include<cstdio>

using namespace std;

int i,j,k,n;

int main()
{
freopen("tije.in","r",stdin);
freopen("tije.out","w",stdout);
scanf("%d",&n);
for(k=n-1;k>=1;k--)
{
    for(i=n;i>=1;i--)
        for(j=1;j<=k;j++)
            printf("%d %d\n",i,i+1);
    for(i=1;i<=k;i++)
        printf("%d 1\n",n+1);
}
return 0;
}