思路是先转换成 $(1,ab)$，再看能否转化成 $(1,cd)$。

结果就过了子任务2/kk

#include <bits/stdc++.h>
#define int long long
using namespace std;
void solve(){
	vector<pair<int, int> > ans;
	int a, b, c, d;
	cin >> a >> b >> c >> d;
	int x = a * b, y = c * d;
	if (x < y || x == 2){
		cout << -1 << '\n';
		return ;
	}
	int m = 1, op = 0;
	ans.push_back({1, a});
	while (1){
		if (x / 2 < y){
			x = y;
			ans.push_back({2 - op, x});
			op = !op;
			if (op){
				if (x == c){
					m ++;
					break;
				}
				ans.push_back({2 - op, d});
			}
			else{
				if (x == d){
					m ++;
					break;
				}
				ans.push_back({2 - op, c});
			}
			m += 2;
			break;
		} else{
			int k = x / 2 + 1;
			x -= k;
			ans.push_back({2 - op, k});
			op = !op;
			m ++;
		}
	}
	cout << m << '\n';
	for (auto i : ans)
		cout << i.first << ' ' << i.second << '\n';
	return ;
}
signed main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int T = 1;
	cin >> T;
	while (T -- ){
		solve();
	}
	return 0;
}