#include<iostream>  
 #include<fstream.h>  
 #include<stdio.h>  
 ifstream f("tije.in");  
 FILE *g=fopen("tije.out","w");  
 int main()  
 {  
    int i,j,i1,n;  
    f>>n;  
    for(i=n-1;i;i--)  
    {  
      for(j=n;j;j--)  
       for(i1=i;i1;i1--)  
        fprintf(g,"%d %d\n",j,j+1);  
       for(i1=i;i1;i1--)  
        fprintf(g,"%d 1\n",n+1);  
    }  
    return 0;  
}