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