#include<bits/stdc++.h>
using namespace std;
#define int long long
using ll = long long;
const int N = 1e6 + 10;
const ll inf = 1ll << 60, mod = 1e9 + 7;

inline int calc(ll x, ll y) {
    static int numx[20], numy[20];
    int lenx = 0, leny = 0;
    while (x > 0) {
        numx[++lenx] = x % 10;
        x /= 10;
    }
    while (y > 0) {
        numy[++leny] = y % 10;
        y /= 10;
    }
    if (lenx != leny) return 9;
    for (int i = lenx; i >= 2; --i) {
        if (numx[i] != numy[i]) {
            return 9;
        }
    }
    int ans = 0;
    for (int i = 1; i <= leny; ++i) {
        ans = max(ans, numy[i]);
    }
    return ans;
}
void solve() {
    int l1, r1, l2, r2; cin >> l1 >> r1 >> l2 >> r2;
    ll l = l1 + l2, r = r1 + r2;
    cout << calc(l, r) << endl;
}
/*
 2
 178 182 83 85
 2 5 3 6
*/
signed main() {
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int _ = 1;
    cin >> _;
    while(_--) solve();
}