python3 代码
from sys import stdin
input=lambda:stdin.readline().strip()
n=int(input())
A=list(map(int,input().split()))
dp1=A[0]
dp2=A[0]
last=0
for i in range(1,n):
x,y=map(int,input().split())
t1=dp1+A[i]-A[i-1]
if last<x:
t2=min(dp2+(x-last)/0.7,dp1+x/0.7)
else:
t2=min(dp2+(last-x)/1.3,dp1+x/0.7)
t3=t1+y/0.7
t4=t2+y/1.3
# print(dp1,dp2)
dp1=min(t1,t4)
dp2=min(t2,t3)
last=y
print("{:.02f}".format(round(dp1,2)))