1227A - Math Problem - CodeForces Solution

import sys
import math
 
 
from decimal import *
 
 
 
  def prime_generator(nr_elemente_prime):
 
 vector_prime=[-1]*nr_elemente_prime
 vector_rasp=[0]*nr_elemente_prime
 
 vector_prime[1]=1
 
 vector_rasp[1]=1
 contor=2
 
 for i in range(2,nr_elemente_prime):
  if vector_prime[i]==-1:
   vector_prime[i]=1
   vector_rasp[contor]=i
   contor=contor+1
  for j in range(i+i,nr_elemente_prime,i):
    if vector_prime[j]==-1:
     vector_prime[j]=i
      
   
 
 set_prime=set(vector_rasp)
 sume_disponibile=set()
 
 for i in range(3,nr_elemente_prime):
  sume_disponibile.add(vector_rasp[i-1]+vector_rasp[i])
 
 
 
rasp_final=""  
 
def transformare_baza(numar,baza):
 
 transformare=""
 while numar>=baza:
  rest=numar%baza
  numar=numar//baza
  transformare+=str(rest)
 
 transformare+=str(numar)
 noua_baza=transformare[::-1]
 return noua_baza
 
 
def bitwise_xor(a,b):
 stringul_1=transformare_baza(a,2)
 stringul_2=transformare_baza(b,2)
 
 lungime=max(len(stringul_1), len(stringul_2))
 raspunsul=0
  
 str_answ=[0]*lungime
 
  
 for i in range(0,lungime):
   j=lungime-1-i
  if len(stringul_1)>i and len(stringul_2)>i:
   if stringul_1[len(stringul_1)-1-i]!= stringul_2[len(stringul_2)-1-i]:
    raspunsul+=2**(i)
    str_answ[i]='1'
  elif len(stringul_1)>i and stringul_1[len(stringul_1)-1-i]=='1':
   raspunsul+=2**(i)
   str_answ[i]='1'
  elif len(stringul_2)>i and stringul_2[len(stringul_2)-1-i]=='1':
   raspunsul+=2**(i)
   str_answ[i]='1'
   
  
 return raspunsul
 
 
def bitwise_or(a,b):
 stringul_1=transformare_baza(a,2)
 stringul_2=transformare_baza(b,2)
 
 lungime=max(len(stringul_1), len(stringul_2))
 raspunsul=0
  
 str_answ=[0]*lungime
 
  
 for i in range(0,lungime):
   j=lungime-1-i
  if len(stringul_1)>i and len(stringul_2)>i:
   if stringul_1[len(stringul_1)-1-i]=='1' or  stringul_2[len(stringul_2)-1-i]=='1':
    raspunsul+=2**(i)
    str_answ[i]='1'
  elif len(stringul_1)>i and stringul_1[len(stringul_1)-1-i]=='1':
   raspunsul+=2**(i)
   str_answ[i]='1'
  elif len(stringul_2)>i and stringul_2[len(stringul_2)-1-i]=='1':
   raspunsul+=2**(i)
   str_answ[i]='1'
   
  
 return raspunsul
def suma_cifre(suma_cifrelor):
 suma_cifr=0
 while suma_cifrelor>0:
  suma_cifr+=suma_cifrelor %10
  suma_cifrelor=suma_cifrelor//10
 return suma_cifr 
 
def cmmdc(x,y):
 maximul=max(x,y)
 minimul=min(x,y)
 while maximul!=minimul and minimul!=0:
  
  dif=maximul-minimul
  raport=dif//minimul
 
  
  
  maximul-=minimul*(raport+1)
  
  a=max(minimul,maximul)
  b=min(minimul, maximul)
  
  maximul=a
  minimul=b
 
 return (maximul)
 
 
dict = {}  
 alfabet = {'a': 1, 'b': 2,'c': 3,'d': 4,'e': 5,'f': 6,'g': 7,'h': 8,'i': 9,'j': 10,'k': 11,'l': 12,'m': 13,'n': 14,'o': 15,'p': 16,'q': 17,'r': 18,'s': 19,'t': 20,'u': 21,'v': 22,'w': 23,'x': 24,'y': 25,'z': 26}
 
contor=0
k=int(input())
while k>0:
 
     n=int(input())
 
 left_left=10**9+1
 left_right=10**9+1
 
 right_right=-1
 right_left=-1
 
 for i in range(0,n):
  a,b=[int(i) for i in sys.stdin.readline().split()]
  if b<left_right:
   left_right=b
   left_left=a
  if a>right_left:
   right_left=a
   right_right=b
   
  
  if right_left<=left_right:
  print(0)
 else:
  print(abs(left_right-right_left))
  
 
 
 
 k-=1