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#include <bits/stdc++.h>
#define pii pair<int,int>
#define f first
#define s second
using namespace std;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int k;
    cin>>k;
    vector<pii>V(92,{-1,-1});
    for(int i=1;i<90;i++)
    {
        if(i%3==1)
            V[i]={i+1,i+2};
        else
            V[i].f=i+1;
    }
    int i=1073741824,j=30;
    while(j>=0)
    {
        if(k>=i)
        {
            k-=i;
            V[3*j+2].s=91;
        }
        i/=2;
        j--;
    }
    cout<<91<<"\n";
    for(int i=1;i<=91;i++)
        cout<<V[i].f<<" "<<V[i].s<<"\n";
    return 0;
}