# include <bits/stdc++.h>
using namespace std;
int n;
int turn_(int x) { return (x-1)%n+1;}
int main() {
//    freopen("in.in","r",stdin);
//    freopen("out.out","w",stdout);

    scanf("%d",&n);

    int m=n; 
    if (n%2==0) n--;
    vector<pair<int,int> > ans;
    for (int i=1;i<=n;i++) {
        if (n!=m) ans.push_back(pair<int,int> (i,n+1));
        for (int j=1;j<=n/2;j++) ans.push_back(pair<int,int> (turn_(i+j),turn_(i+n-j)));
    }

    for (auto o : ans) printf("%d %d\n",o.first,o.second);

    return 0;
}