#include<bits/stdc++.h>
using namespace std;
int n;
int main(){
    cin>>n;
    if(n&1){
        for(int i=0;i<n;i++){
            int r=(i-1+n)%n,l=(i+1)%n;
            for(int j=1;j<=n/2;j++){
                cout<<l+1<<" "<<r+1<<"\n";
                l++,l%=n;
                r+=n-1,r%=n;
            }
        }
    } else {
        for(int i=1;i<n;i++){
            int r=(i-1+n)%n,l=(i+1)%n;
            cout<<1<<" "<<i+1<<"\n";
            if(!r)r=n-1;
            if(!l)l=1;
            for(int j=1;j<n/2;j++){
                cout<<l+1<<" "<<r+1<<"\n";
                l++,l%=n;
                r+=n-1,r%=n;
                if(!r)r=n-1;
                if(!l)l=1;
            }
        }
    }
    return 0;
}