#include<bits/stdc++.h>
#define int long long
#define endl "\n"
#define ll long long
#define PII std::pair<int,int>
using namespace std;
const int maxn = 1e5 + 5;
bool cmp(PII p1, PII p2) {
    if (p1.second == p2.second) return p1.first < p2.second;
    return p1.second < p2.second;
}
int cmpp[20];
signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int T; cin >> T;
    while (T--) {
        int n; cin >> n;
        vector<PII> G(n + 1);
        for (int i = 1; i <= n; ++i) {
            cin>>G[i].first>>G[i].second;
        }
        sort(G.begin() + 1, G.end(), cmp);
        int m = G[1].second;
        int kase = 0, temp = m;
        while (temp) {
            temp >>= 1;
            kase++;
        }
        cmpp[0] = 1;
        for (int i = 1; i <= 20; ++i) cmpp[i] = cmpp[i - 1] * 2;
        for (int i = 2; i <= n; ++i) {
            int mi = G[i].first & cmpp[kase] - 1;
            int size = G[i].second - G[i].first;
            if (mi + size >= m) continue;
            m = mi + size;
            while (m <= cmpp[kase - 1] - 1) kase--;
        }
        cout << m << endl;
    }
    return 0;
}