#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MP make_pair
mt19937 rnd(time(0));
int find(ll x)
{
	ll ans=0;
	while(x)ans=max(ans,x%10),x/=10;
	return ans;
}
int main(){
	ios::sync_with_stdio(false);
	// freopen("Otomachi_Una.in","r",stdin);
	// freopen("Otomachi_Una.out","w",stdout);
	int T;cin>>T;
	while(T--)
	{
		ll la,lb,ra,rb;cin>>la>>ra>>lb>>rb;
		ll l=la+lb,r=ra+rb;
		if(l/10==r/10)cout<<find(r)<<endl;
		else cout<<9<<endl;
	}
	return 0;
}