#140 백준 파이썬 [2455] 지능형 기차

https://www.acmicpc.net/problem/2455

 

#Solution

passenger = []
in_train = 0
result = 0

for _ in range(4):
    passenger.append(list(map(int, input().split())))
    
for [out_p, in_p] in passenger:
    in_train += in_p - out_p
    result = max(result, in_train)

print(result)