#include <cstdio>   

using namespace std;

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

int N;   

    void solve()   
    {   
        int i,j,k;   
        for(k = N - 1; k; --k)   
        {   
            for(i = N; i; --i)   
               for(j = 1; j <= k;j++)   
                 printf("%d %d\n",i, i+1);   
            for(j=1;j<=k;++j)   
                 printf("%d %d\n", N + 1, 1);   
        }   
    }   
    
    int main()   
    {   
        freopen("tije.in","r",stdin);   
        freopen("tije.out","w",stdout);   
        
        scanf("%d", &N);   
        solve();   
        
        return 0;
    }