#include<stdio.h>
long int n,i,j,k,u;
int main()
{   FILE *f,*g;f=fopen("tije.in","r");g=fopen("tije.out","w");
    fscanf(f,"%ld",&n);u=1;
    for(i=n-1;i>=1;i--)
    { for(j=1;j<=i;j++)
       fprintf(g,"%ld %ld\n",u,n+1);
      for(k=1;k<=n;k++)
       for(j=1;j<=i;j++)
	fprintf(g,"%ld %ld\n",k+1,k);
    }
    fcloseall();
    return 0;
}