N=int(input())
l=0
r=10**10
L=[]
R=[]
for i in range(N):
  a,b=map(int,input().split())
  L.append(a-1)
  R.append(b-1)
L.sort()
R.sort()
for i in range(N):
  l=max(l,L[i]-i)
for i in range(N):
  r=min(r,R[i]-i)
if l>r:
  print(0)
  exit()
ans=r-l+1
if ans>2*10**2:
  print(ans)
p=[0]
print(p[1])