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#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>
using namespace std;
#define sim template <class c
#define mor > muu & operator<<(
#define ris return *this
#define R22(r) sim>typename enable_if<1 r sizeof(dud<c>(0)),muu&>::type operator<<(c g) {
#define R23(r) sim, size_t N>typename enable_if<N r std::tuple_size<c>::value,muu&>::type operator<<(zub<c,N> 
sim> struct rge {c b, e;};
sim> rge<c> range(c i, c j) {return rge<c>{i, j};}
sim> auto dud(c*r)->decltype(cerr << *r);
sim> char dud(...);
sim, size_t N> struct zub {c x;};
struct muu {
	#ifdef LOCAL
	#define qel(t) sim, class d, class...e mor t<c,d,e...> r){ris << *(d*)&r;}
	qel(queue) qel(priority_queue) qel(stack)
	stringstream a;
	~muu() {cerr << a.str() << endl;}
	R22(<) a << boolalpha << g; ris;}
	R22(==) ris << range(begin(g), end(g));}
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i)
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
	sim, class m mor pair <m,c>r){ris << "(" << r.first << ", " << r.second << ")";}
	sim, class...m mor tuple<c,m...>r){ris << zub<tuple<c,m...>,0>{r};}
	R23(!=) g) {ris << (N ? ", " : "(") << get<N>(g.x) << zub<c, N + 1>{g.x};}
	R23(==) ) {ris << ")";}
	#else
	sim mor const c&){ris;}
	#endif
};
#define imie(r...) "[" #r ": " << (r) << "] "
#define arr(a, i) "[" #a imie(i) ": " << a[i] << "] "
#define range(a, b) "[[" #a ", " #b "): " << range(a, b) << "] "
#define debug muu() << __FUNCTION__ << "#" << __LINE__ << ": "
#define arr2(a, i, j) "[" #a imie(i) imie(j) ": " << a[i][j] << "] "
#define imask(r...) "[" #r ": " << bitset<8 * sizeof(r)>(r) << "] "
using pii = pair <int, int>; using ll = long long; using ull = unsigned long long;
using ld = long double; using Pii = pii; using vpii = vector<pii>; using unt = unsigned int;
using vi = vector <int>; using pll = pair <ll, ll>; using vpll = vector <pll>;
sim> void mini(c &a, c b) {if (a > b) a = b;} sim> void maxi(c &a, c b) {if (a < b) a = b;}
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
sim, class cmp = less<c> > using ordered_set = tree<c, null_type, cmp, rb_tree_tag, tree_order_statistics_node_update>; 
const int maxn = 130;

int k;
vi V[maxn];
int main()
{
    int ind = 1;
    int n = 100;
    scanf("%d", &k);
    while(k)
    {
        if (k % 2 == 0)
        {
            V[ind].push_back(ind + 1);
            V[ind].push_back(ind + 2);
            V[ind+1].push_back(ind + 2);
            ind += 2;
            k /= 2;
        }
        else
        {
            V[ind].push_back(n);
            V[ind].push_back(ind + 1);
            ind += 1;
            k -= 1;
        }
    }
    printf("%d\n", n);
    for(int i = 1; i <= n; ++i)
    {
        while(V[i].size() != 2u)
            V[i].push_back(-1);
        printf("%d %d\n", V[i][0], V[i][1]);
    }
}