#!/usr/bin/env python

elves = []

with open('input') as f:
    elf = []
    for line in f:
        if line == "\n":
            elves.append(elf)
            elf = []
        else:
            calories = int(line)
            elf.append(calories)

most = 0

for elf in elves:
    calories = sum(elf)
    if calories > most:
        most = calories

print(most)