N = int(input())
S = input()
dp = [0] * 3

if S[0] == "-":
    dp[0] = 1
elif S[0] == "0":
    dp[1] = 1
else:
    dp[2] = 1

for s in S[1:]:
    new_dp = dp[:]
    if s == "-":
        new_dp[0] = max(new_dp[0], dp[0] + 1)
    elif s == "0":
        new_dp[1] = max(new_dp[1], dp[0] + 1)
    else:
        new_dp[2] = max(new_dp[2], dp[1] + 1)
        new_dp[2] = max(new_dp[2], dp[2] + 1)

    dp = new_dp

print(max(dp))