#include<cstdio>

using namespace std;

const char iname[]="tije.in";
const char oname[]="tije.out";

int n,i,j,k;

int main()
{
    freopen(iname,"r",stdin);
    freopen(oname,"w",stdout);
    scanf("%d",&n);
    for(i=1;i<n;++i)
    {
        for(j=n;j;--j)
            for(k=i;k;--k)
                printf("%d %d\n",j,j+1);
        for(k=i;k;--k)
            printf("%d %d\n",n+1,1);
    }

    fclose(stdin);
    fclose(stdout);

    return 0;
}