#include <bits/stdc++.h>
#include <atcoder/all>
using ll = long long;
using namespace std;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define rrep(i, s, t) for (ll i = (ll)(t) - 1; i >= (ll)(s); i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)

template <typename T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <typename T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		std::cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

void solve() {
  int m=99;
  cout<<m<<"\n";
  rep(i,0,m) cout<<i+1<<" "<<i+2<<"\n";
}

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