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#include <bits/stdc++.h>

using namespace std;

typedef vector<int> VI;
typedef long long LL;
#define FOR(x, b, e) for(int x = b; x<= (e); ++x)
#define FORD(x, b, e) for(int x = b; x>= (e); --x)
#define REP(x, n) for(int x = 0; x<(n); ++x)
#define VAR(v, n)typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define PB pushback
#define ST first
#define ND second

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int k;
    cin >> k;

    if (k == 1) {
        cout << "2\n";
        cout << "2 -1\n";
        cout << "-1 -1\n";
    }

    else {
        vector<bool> a;
        while (k > 0) {
            a.push_back(k % 2);
            k /= 2;
        }
        int s = a.size() - 1;

        VI graph[2 * s + 3];
        FOR(i, 1, 2*s - 1) {
            graph[i].push_back(i + 1);
        }
        graph[2*s].push_back(2*s + 2);
        FOR(i, 1, s - 1) {
            graph[2*i - 1].push_back(2*i + 1);
        }
        graph[2*s - 1].push_back(2*s + 2);
        FOR(i, 0, s - 2) {
            if (a[i]) {
                graph[2*i + 2].push_back(2*s + 2);
            }
        }

        if (a[s - 1]) {
            graph[2*s].push_back(2*s + 1);
            graph[2*s + 1].push_back(2*s + 2);
        }

        cout << 2*(s + 1) << "\n";
        FOR(i, 1, 2*s + 2) {
            if (graph[i].size() == 0) {
                cout << "-1 -1\n";
            }
            else if (graph[i].size() == 1) {
                cout << graph[i][0] << " -1\n";
            }
            else {
                cout << graph[i][0] << " " << graph[i][1] << "\n";
            }
        }
    }

    return 0;
}