#include<fstream>
 using namespace std;
 ifstream f("dame.in");
 ofstream g("dame.out");
 int n,i,j,a[101],b[101],c[202];
 int main()
    {f>>n;

        for(i=2; i<=n; i+=2) a[i/2]=i;
       // for(i=1; i<=n/2; ++i) g<<a[i];
        for(i=1; i<=n; i+=2) b[n/2+i/2+1]=i;
        //for(i=1; i<=n; ++i)  {if(b[i]==0) b[i]=b[i+1];}
        //for(i=1; i<=n; ++i)  {if(b[i]==b[i+1]) b[i+1]=b[i+2];}
        // for(i=1; i<=n; ++i) g<<b[i];
        if(n == 2)
        g<<"1"<<'\n'<<"1"<<" "<<"1";
        if(n == 3)
        g<<"2"<<'\n'<<"1"<<" "<<"1"<<'\n'<<"2"<<" "<<"3";

        return 0;
    }