N=int(input())
S=input()
result=[0]*N
a,b,c=0,0,0
for i in range(N):
  if S[i]=='-':
    a+=1
  elif S[i]=='0':
    b=max(b,a+1)
  else:
    c=max(a+1,b+1,c+1)
print(max(a,b,c))