# include <cstdio>
using namespace std;
int n,m,i,j;
int main () {
    freopen("tije.in","r",stdin);
    freopen("tije.out","w",stdout);
    scanf("%d\n",&n);
    m=n;
    n--;
    while(n!=0){
        for(i=1;i<=n;i++)
            printf("1 %d\n",m+1);
        for(j=1;j<=m;j++)
            for(i=1;i<=n;i++)
                printf("%d %d\n",j+1,j);
        n--;
    }
    return 0;
}