#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int brehl[10000000];
int brehp[10000000];

int mindelka;

#define min(a,b) ((a) < (b) ? (a) : (b))

int main()
{
  int num;
  scanf("%d", &num);
  for (int k = 0; k < num; k++)
  {
    int delka;
    scanf("%d", &delka);
    mindelka = 1000000;
    for (int i = 0; i < delka; i++)
    {
      scanf("%d%d", &brehl[i], &brehp[i]);
      for (int j = i; j >= 0; j--)
      {
  	mindelka = min(mindelka, brehp[i] - brehl[j] + i - j);
	mindelka = min(mindelka, brehp[j] - brehl[i] + i - j);
      }
    }
    printf("K prechodu reky je treba %d pontonu.\n", mindelka);
  }
  return 0;
}