#include<stdio.h>

int fct(int a,int b)
{if(a%b==0)return 0;
if(b%a==0)return 0;
return 1;
}


int main()
{freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
int i,j,n,k=0;
scanf("%i",&n);
for(i=1;i<=n;i++)
for(j=1;j<=n;j++)
{if(i==1 || j==1){++k;printf("%i %i \n",i,j);}
else 
if (fct(i,j))
{++k;printf("%i %i \n",i,j);}
}
printf("%i",k);
return 0;
}