#include <iostream>
#include <algorithm>
#include <string.h>
using namespace std;
int n;
int main()
{
	cin>>n;
	for(int i=0;i<n;i++)
		cout<<(2*i)%n+1<<' '<<(2*i+1)%n+1<<endl;
	return 0;
}
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define mp make_pair
#define pl pair<ll, ll>
#define vl vector<ll>
#define fastIO ios_base::sync_with_stdio(false);cin.tie(NULL);
#define mod 1000000007
#define N 100005


int main()
{
    fastIO
    string s; cin>>s;
    ll n = s.size();
    string ans;
    for(ll i=0;i<n;i++)
    {
        if(s[i]=='.')
        break;
        ans.pb(s[i]);
    }
    cout<<ans<<"\n";

}