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#include <bits/stdc++.h>
#define fi first
#define sc second
#define forn(i,p,k) for(int i=(p);i<=(k);++i)
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
int L[101],R[101];
int akt=99;

void solve(const int &x)
{
    if(x==1)    return;
    solve(x>>1);
    L[akt]=akt+1;
    akt--;
    L[akt]=akt+1;
    R[akt]=akt+2;
    akt--;
    if(x&1)
    {
        L[akt]=akt+1;
        R[akt]=100;
        akt--;
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    int k;
    cin>>k;
    solve(k);
    L[1]=akt+1;
    cout<<100<<"\n";
    forn(i,1,100)   cout<<(L[i]==0?-1:L[i])<<" "<<(R[i]==0?-1:R[i])<<"\n";
    return 0;
}