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#include <bits/stdc++.h>
using namespace std;

int k;
vector<int> v[107];
int main() {
    ios_base :: sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> k;
    int pp = 1, a=2, b=3;
    for (int l=1; l<=k; l*=2)
    {
        v[pp].push_back(a);
        v[pp].push_back(b);

        if ((k&l)>0){
            v[a].push_back(100);
        }

        v[a].push_back(b+1);
        v[b].push_back(b+1);

        pp+=3;
        a+=3;
        b+=3;
    }

    cout<<b-1<<"\n";
    for (int i=1; i<=b-1; i++){
        if (v[i].size()==2 )
            cout<<min(v[i][1], b-1)<<" "<<min(v[i][0], b-1)<<"\n";
        else if (v[i].empty())
            cout<<-1<<" "<<-1<<"\n";
        else
            cout<<min(v[i][0], b-1)<<" -1\n";
    }

}