#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());

const int N = 1010;

int n, m;
int a[N], b[N];

int iabs(int x) { return x < 0 ? -x : x; }

void solve() {
  int cl, cr;
  scanf("%d%d%d", &n, &cl, &cr);
  m = 0;
  for (int i = 2; i <= n; ++i) {
    int l, r;
    scanf("%d%d", &l, &r);
    if (max(cl, l) > min(cr, r)) {
      ++m;
      a[m] = cl; b[m] = cr;
      cl = l;
      cr = r;
    } else {
      cl = max(cl, l);
      cr = min(cr, r);
    }
  }
  ++m;
  a[m] = cl;
  b[m] = cr;
  int ans = 0;
  if (m > 1) {
    int x;
    if (a[1] < a[2])
      x = b[1];
    else
      x = a[1];
    for (int i = 2; i < m; ++i) {
      if (a[i] == b[i]) {
        ans += (iabs(a[i] - x) + 1) / 2;
        x = a[i];
      } else if (x < a[i]) {
        int v = (a[i] - x + 1) / 2;
        ans += v;
        if (a[i] < a[i + 1]) {
          x += v * 2;
        } else {
          x = a[i];
        }
      } else {
        int v = (x - b[i] + 1) / 2;
        ans += v;
        if (a[i] < a[i + 1]) {
          x = b[i];
        } else
          x -= v * 2;
      }
    }
    if (x < a[m])
      ans += (a[m] - x + 1) / 2;
    else ans += (x - b[m] + 1) / 2;
  }
  printf("%d\n", ans);
}

int main() {
  int t;
  scanf("%d", &t);
  while (t--)
    solve();
  return 0;
}