#include<cstdio>
int n;
void read()
{
    freopen("tije.in","r",stdin);
    freopen("tije.out","w",stdout);
    scanf("%d",&n);
}
void mut(int nm,int sursa)
{
    int dest=(sursa+1)%(n+1);
    if(dest==0)
        dest=n+1;
    for(int i=1;i<=nm;++i)
        printf("%d %d\n",sursa,dest);
}
void solve()
{
    for(int i=n-1;i>=1;--i)
    {
        for(int j=n;j>=1;--j)
            mut(i,j);
        mut(i,n+1);
    }
}
int main()
{
    read();
    solve();
    return 0;
}