#include<cstdio>
using namespace std;
int n;
int main(){
	scanf("%d",&n);
	for(int i=1,t=(n-1)/2*2+1;i<=t;++i){
		for(int T=t/2,j=i,k=i%t+1;T--;j=(j+t-2)%t+1,k=k%t+1) printf("%d %d\n",j,k);
		if(n%2==0) printf("%d %d\n",(i+t/2)%t+1,n);
	}
	return 0;
}