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

int main(){
    int n;
    cin>>n;
    cout<<"100\n";
    int uw=1;

    for(long long i=1;i<=n;i*=2){
        cout<<uw+1<<' '<<uw+2<<'\n';
        cout<<uw+2<<' '<<((n&i)?"100":"-1")<<'\n';
        uw+=2;
    }
    for(int i=uw;i<=100;i++){
        cout<<"-1 -1\n";
    }
}