#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
using namespace std;
int main(){
    int T=0;
    int t;cin>>t;while(t--){
        T++;
        long long x1,x2,y1,y2,x,y;
        cin>>x1>>x2>>y1>>y2;
        // if(T==52)cout<<x1<<","<<x2<<","<<y1<<","<<y2<<endl;
        // else continue;
        x=x1+y1;y=x2+y2;
        if(y-x>=10)cout<<9<<endl;
        else{
            long long k=x,cnt=0;
            while(k){
                cnt=max(cnt,k%10);
                k/=10;
            }
            if(cnt==9)cout<<9<<endl;
            else
            if(y%10<x%10)cout<<9<<endl;
            else cout<<max(cnt,y%10)<<endl;
        }
    }
}