#include<stdio.h>   
int main(){
	int n,j,i,k;
	freopen("tije.in","r",stdin);   
    freopen("tije.out","w",stdout);
    scanf("%d",&n);   
    for(i=n;i>1;i--){
        for(j=n-1;j>0;--j){
			printf("%d %d\n",i,n+1);
		}
        for(j=n-i+1;j>0;--j){
			printf("%d %d\n",i-1,i);
		}
        for(j=i-2;j>0;--j){
            for(k=n-i;k>0;--k){
				printf("%d %d\n",j,j+1);
			}
			printf("%d %d\n",n+1,j+1);
			printf("%d %d\n",j,i);
		}
        for(j=n-i+1;j>0;--j){
			printf("%d %d\n",n+1,1);
		}
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}