#include <bits/stdc++.h>

using namespace std;

#define endl '\n'

void solve(){
	int l1, r1, l2, r2;
	cin >> l1 >> r1 >> l2 >> r2;
	// int L1 = l1.back() - '0', R1 = r1.back() - '0', L2 = l2.back() - '0', R2 = r2.back() - '0';
	int ans = 0;
	while (l1 || r1 || l2 || r2){
		int x1 = l1 % 10, y1 = r1 % 10, x2 = l2 % 10, y2 = r2 % 10;
	
		if (y1 < x1 ) y1 += 10;
		if (y2 < x2) y2 += 10;
		for (int i = x1; i <= y1; i ++){
			for (int j = x2; j <= y2; j ++){
				ans = max(ans, (i + j) % 10);
			}
		}
		l1 /= 10, l2 /= 10, r1 /= 10, r2 /= 10;
		
	}
	
	
	cout << ans << endl;
	
	
	
}


int main(){
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	
	int t = 1;
	cin >> t;
	while (t --) solve();
}