#include<bits/stdc++.h>
#define int long long
#define x first
#define y second
using namespace std;
const int N = 30,M = 1<<24,mod = 998244353,INF=1e9;
typedef pair<int,int>PII;
int n;
int get(int x)
{
    if(x<1) x+=n;
    if(x>n) x-=n;
    return x;
}
void solve()
{
    cin>>n;
    int ok =0;
    if(~n&1)    ok=n--;
    int k = n/2;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=k;j++)
            printf("%lld %lld\n",get(i-j+1),get(i+j));
        if(ok)  printf("%lld %lld\n",get(i+k+1),ok);
    }
}
signed main()
{
    int T =1;
    //cin>>T;
    while(T--)
    {
        solve();
    }
    return 0;
}