#include <stdio.h>

int n, i, j, k;

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