n = int(input())
s = input()
rp = [0] * (n+1)
rm = [0] * (n+1)
cp = [0] * n
cm = [0] * n
for i in range(n):
    if s[i] == "+":
        cp[i] = 1
    elif s[i] == "-":
        cm[i] = 1
for i in range(1, n+1):
    rp[i] = rp[i-1] + cp[i-1]
    rm[i] = rm[i-1] + cm[i-1]
mx = -float("inf")
for i in range(n):
    mx = max(mx, rm[i+1] + (rp[-1]-rp[i])+(s[i] == "0"))
print(mx)