from __future__ import annotations
import sys
from dataclasses import dataclass

@dataclass
class E:
    v: int
    p: E
    n: E

V0 = None
p = None
L = []
for l in sys.stdin.read().splitlines():
    e = E(int(l),p,None)
    L.append(e)
    if l == "0":
        V0 = e
    if p is not None:
        p.n = e
    p = e
L[-1].n = L[0]
L[0].p = L[-1]

def swap(l,m):
    k = l.p
    n = m.n
    k.n = m
    n.p = l
    l.n = n
    m.p = k
    l.p = m
    m.n = l

for l in L:
    if l.v > 0:
        for _ in range(l.v):
            swap(l,l.n)
    elif l.v < 0:
        for _ in range(-l.v):
            swap(l.p,l)

S = 0
s = V0
for i in range(3000+1):
    if i in [1000,2000,3000]:
        S += s.v
    s = s.n
print(S)