N=int(input())
S=input()
L=[]
l=0
for i in range(N):
    if S[i]=="-":
        l+=1
    L.append(l)
R=[]
r=0
for i in range(N-1,-1,-1):
    if S[i]=="+":
        r+=1
    R.append(r)
R.reverse()
R.append(0)
ans=0
for i in range(N):
    if S[i]=="0":
        ans=max(ans,L[i]+R[i+1]+1)
    else:
        ans=max(ans,L[i]+R[i+1])
print(ans)