#include<bits/stdc++.h>
#define fore(i,l,r)	for(int i=(int)(l);i<(int)(r);++i)
#define fi first
#define se second
#define endl '\n'
#define ull unsigned long long
#define ALL(v) v.begin(), v.end()
#define Debug(x, ed) std::cerr << #x << " = " << x << ed;

const int INF=0x3f3f3f3f;
const long long INFLL=1e18;

typedef long long ll;

void solve(){
    ll l1, r1, l2, r2;
    std::cin >> l1 >> r1 >> l2 >> r2;
    std::vector<std::vector<int>> d1(10), d2(10);
    ll pow = 1;
    fore(i, 1, 10){
        d1[i].push_back(l1 / pow % 100);
        fore(j, 1, 100){
            if(l1 / pow * pow + j * pow <= r1)
                d1[i].push_back(l1 / pow % 100 + j);
        }
        pow *= 10;
    }

    pow = 1;
    fore(i, 1, 10){
        d2[i].push_back(l2 / pow % 100);
        fore(j, 1, 100){
            if(l2 / pow * pow + j * pow <= r2)
                d2[i].push_back(l2 / pow % 100 + j);
        }
        pow *= 10;
    }

    int ans = 0;
    fore(i, 1, 10)
        for(auto x : d1[i])
            for(auto y : d2[i]){
                if(i == 1) ans = std::max({ans, (x + y) % 10, (x + y) / 10 % 10});
                else ans = std::max(ans, (x + y) / 10 % 10);
            }

    std::cout << ans << endl;
}

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