n=int(input())
X=10**7
p=[]
for _ in range(n):
  x,y=map(int,input().split())
  p+=[(x+X,y+X)]
M=998244353
a=0
for i in range(n):
  sx,sy=p[i-1]
  tx,ty=p[i]
  if sx<tx:
    a-=(sy+ty)*(tx-sx)
  else:
    a+=(sy+ty)*(sx-tx)
print(a*pow(2,M-2,M)%M)