#include <bits/stdc++.h>
using i64 = long long;
using namespace std;
const int N = 1e5 + 5;
// const int B = 340;
// const int M = 5e3 + 5;
// const int base = 1753591;
// const int mod = 998244353;
const int mod = 1e9 + 7;
// const double pi = acos(-1);

void solve()
{
    int a, b, c, d;
    cin >> a >> b >> c >> d;
    int ans = 0;
    for (int i = 0; i <= 10 && a + i <= b; i++)
        for (int j = 0; j <= 10 && c + j <= d; j++)
        {
            string s = to_string(i + j + a + c);
            for (char c : s)
                ans = max(ans, c - '0');
        }
    cout << ans << '\n';
}
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    cin >> t;
    cout << fixed << setprecision(10);
    while (t--)
        solve();
}