import sys
input = sys.stdin.readline

N=int(input())
S=input().strip()

DP0=[0]*N
DP1=[0]*N
DP2=[0]*N

for i in range(N):
    x=S[i]
    DP2[i]=DP2[i-1]
    DP1[i]=DP1[i-1]
    DP0[i]=DP0[i-1]

    if x=="+":
        DP2[i]=max(DP2[i],DP2[i-1]+1,DP1[i-1]+1,DP0[i-1]+1)
    elif x=="0":
        DP1[i]=max(DP1[i],DP0[i-1]+1)
    else:
        DP0[i]=max(DP0[i],DP0[i-1]+1)

print(max(DP0[-1],DP1[-1],DP2[-1]))