#pragma GCC optimize(2)
#include <bits/stdc++.h>
#define int long long
//#define pi 3.1415926
typedef long long ll;
using namespace std;
int mod=998244353;

int fp(int a,int b){
	int ans=1;
	while(b){
		if(b&1) ans*=a,ans%=mod;
		a*=a,a%=mod;
		b>>=1;
	}
	return ans;
}

void solve(){
	int la,ra,lb,rb;cin>>la>>ra>>lb>>rb;
	int a=la+lb,b=ra+rb;
	if(b-a>=10)	cout<<9<<"\n";
	else{
		if(a/10!=b/10) cout<<9<<"\n";
		else{
			int maxi=0;
			while(b!=0) maxi=max(maxi,b%10),b/=10;
			cout<<maxi<<"\n";
		} 
	}
}

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