#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cctype>

#include <algorithm>
#include <random>
#include <bitset>
#include <queue>
#include <functional>
#include <set>
#include <map>
#include <vector>
#include <chrono>
#include <iostream>
#include <limits>
#include <numeric>

#define LOG(FMT...) fprintf(stderr, FMT)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

template <class T>
istream& operator>>(istream& is, vector<T>& v) {
  for (T& x : v)
    is >> x;
  return is;
}

template <class T>
ostream& operator<<(ostream& os, const vector<T>& v) {
  if (!v.empty()) {
    os << v.front();
    for (int i = 1; i < v.size(); ++i)
      os << ' ' << v[i];
  }
  return os;
}

int main() {
#ifdef ELEGIA
  freopen("test.in", "r", stdin);
  int nol_cl = clock();
#endif
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int T;
  cin >> T;
  while (T--) {
    int n;
    cin >> n;
    vector<int> x(n), y(n);
    int ans = 0, gu = 0;
    for (int i = 0; i < n; ++i) {
      cin >> x[i] >> y[i];
      if (x[i] == 2)
        gu = max(gu, x[i] + y[i] + 1);
      ans = max(ans, x[i] + y[i]);
    }
    if (gu <= ans) {
      cout << ans << '\n';
    } else {
      bool fl = false;
      for (int i = 0; i < n; ++i)
        if (x[i] == 1 && x[i] + y[i] == ans)
          fl = true;
      if (fl) ++ans;
      cout << ans << '\n';
    }
  }

#ifdef ELEGIA
  LOG("Time: %dms\n", int ((clock()
          -nol_cl) / (double)CLOCKS_PER_SEC * 1000));
#endif
  return 0;
}