#!/usr/bin/env python3

with open('input.txt', 'r') as f:
    in_list = f.readlines()


in_list = [x.strip() for x in in_list]

in_list = [int(x) for x in in_list]
# print(in_list)

freq = set()

res = 0
i = 0
while True:
    if i == len(in_list):
        i = 0
    res += in_list[i]

    if res in freq:
        break
    
    freq.add(res)
    i += 1

print(res)