#include <bits/stdc++.h>

inline int calc(long long x) {
  int res = 0;
  while (x) {
    res = std::max(res, int(x % 10));
    x /= 10;
  }
  return res;
}

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  std::cout.tie(nullptr);

  int testCase = 1;
  std::cin >> testCase;
  while (testCase--) {
    int l, r, x, y;
    std::cin >> l >> r >> x >> y;
    long long min = l + x, max = r + y;
    if (max - min + 1 >= 10) { std::cout << "9\n"; }
    else {
      int ans = 0;
      for (long long i = min; i <= max; ++i)
        ans = std::max(ans, calc(i));
      std::cout << ans << '\n';
    }
  }

  return 0;
}