#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
ll gcd(ll a, ll b){
	if(b==0) return a;
	return gcd(b, a%b);
}
int main()
{
	ll a, b, c, d;
	cin>>a>>b>>c>>d;
	ll x=abs(a*d-b*c);
	cout<<x<<endl;
	for(int i=0; i<x; i++){
		cout<<i<<" "<<0<<endl;
	}
	return 0;
}