#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include<deque>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include <stack>

#ifdef LOCAL
template <class T, size_t size = std::tuple_size<T>::value> std::string to_debug(T, std::string s = "") requires(not std::ranges::range<T>);
std::string to_debug(auto x) requires requires(std::ostream& os) { os << x; } { return static_cast<std::ostringstream>(std::ostringstream() << x).str(); }
std::string to_debug(std::ranges::range auto x, std::string s = "") requires(not std::is_same_v<decltype(x), std::string>) {
  for (auto xi : x) { s += ", " + to_debug(xi); }
  return "[" + s.substr(s.empty() ? 0 : 2) + "]";
}
template <class T, size_t size> std::string to_debug(T x, std::string s) requires(not std::ranges::range<T>) {
  [&]<size_t... I>(std::index_sequence<I...>) { ((s += ", " + to_debug(get<I>(x))), ...); }(std::make_index_sequence<size>());
  return "(" + s.substr(s.empty() ? 0 : 2) + ")";
}
#define debug(...) std::cerr << __LINE__ << ": (" #__VA_ARGS__ ") = " << to_debug(std::tuple(__VA_ARGS__)) << "\n"
#else
#define debug(x...)
#endif

using i64 = long long;
#define int long long

void solve()
{
#define tests
    int n; std::cin >> n; std::vector<std::pair<int, int>> a(n); for (auto&[l, r] : a) {std::cin >> l >> r;}
    
    std::sort(std::begin(a), std::end(a)); std::deque<std::pair<int, int>> Q{std::begin(a), std::end(a)}; 
    std::priority_queue<int, std::vector<int>, std::greater<>> heap;

    int x{}; int ans{}; while (true) {
        while (not std::empty(heap) and heap.top() < x) {heap.pop();}
        if (std::empty(Q) and std::empty(heap)) {break ;} if (std::empty(heap)) {x = Q.front().first;}
        while (not std::empty(Q) and Q.front().first == x) {heap.push(Q.front().second); Q.pop_front();}
        heap.pop(); ans += 1; x += 1;
    }

    std::cout << ans << "\n";
}
 
signed main()
{
    std::cin.tie(nullptr)->sync_with_stdio(false);
    int _{1};
#ifdef tests
    std::cin >> _;
#endif
    while(_--) solve();
    return 0;
}