#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <vector>

using namespace std;

#define FOR(prom, a, b) for(int prom = (a); prom < (b); prom++)
#define FORD(prom, a, b) for(int prom = (a); prom > (b); prom--)
#define FORDE(prom, a, b) for(int prom = (a); prom >= (b); prom--)

#define DRI(a) int a; scanf("%d ", &a);
#define DRII(a, b) int a, b; scanf("%d %d ", &a, &b);

#define RI(a) scanf("%d ", &a);
#define RII(a, b) scanf("%d %d ", &a, &b);

#define PB push_back
#define MP make_pair

#define ll long long
#define ull unsigned long long

#define MM(co, cim) memset((co), (cim), sizeof((co)))

#define DEB(x) cerr << ">>> " << #x << " : " << x << endl;

int n, k, a, b, li, lj, pi, pj, res;

int main ()
{
  scanf("%d", &n);
  FOR(q, 0, n)
  {
    scanf("%d", &k);
    scanf("%d%d", &a, &b);
    li = pi = 0;
    lj = a;
    pj = b;
    res = b - a;
    FOR(i, 1, k)
    {
      scanf("%d%d", &a, &b);
      if (a > (lj - (i - li)))
      {
        li = i;
        lj = a;
      }
      if (b < (pj + (i - pi)))
      {
        pi = i;
        pj = b;
      }
      res = min(res, pj - lj + abs(pi - li));
    }
    printf("K prechodu reky je treba %d pontonu.\n", res);
  }
  return 0;
}