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

#include <atcoder/all>
using namespace atcoder;

using mint = modint998244353;
using vm = vector<mint>;
using vvm = vector<vm>;
inline ostream &operator<<(ostream &os, const mint x)
{
    return os << x.val();
};
inline istream &operator>>(istream &is, mint &x)
{
    long long v;
    is >> v;
    x = v;
    return is;
};

struct Fast
{
    Fast()
    {
        std::cin.tie(nullptr);
        ios::sync_with_stdio(false);
        cout << setprecision(10);
    }
} fast;

template <class T>
inline void chmin(T &a, T b)
{
    if (a > b) a = b;
}
template <class T>
inline void chmax(T &a, T b)
{
    if (a < b) a = b;
}

#define all(a) (a).begin(), (a).end()
#define contains(a, x) ((a).find(x) != (a).end())
#define rep(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rrep(i, a, b) for (int i = (int)(b) - 1; i >= (a); i--)
#define YN(b) cout << ((b) ? "YES" : "NO") << "\n";
#define Yn(b) cout << ((b) ? "Yes" : "No") << "\n";
#define yn(b) cout << ((b) ? "yes" : "no") << "\n";

using ll = long long;
using vl = vector<ll>;
using vvl = vector<vl>;
using vi = vector<int>;
using vvi = vector<vi>;

void solve()
{
    const int n = 100;
    cout << n << "\n";
    rep(i, 0, n) cout << (i + 1) << " " << ((i + 1) % n + 1) << "\n";
}

int main()
{
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
}