#include <stdio.h>

#define FIN "tije.in"
#define FOUT "tije.out"

int N;

int main(void)
{
    int i, j, k;

    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);

    scanf("%d", &N);

    for (i = N-1; i > 0; --i)
    {
        for (j = N; j > 0; --j)
            for (k = i; k; --k)
                printf("%d %d\n", j, j+1);
        for (j = i; j; --j)
            printf("%d 1\n", N+1);
    }

    return 0;
}