N=int(input())
S=list(input())
m_sm=[0]
z_sm=[0]
p_sm=[0]
for s in S:
    if s=="-":
        m_sm.append(m_sm[-1]+1)
        z_sm.append(z_sm[-1])
        p_sm.append(p_sm[-1])
    elif s=="0":
        m_sm.append(m_sm[-1])
        z_sm.append(z_sm[-1]+1)
        p_sm.append(p_sm[-1])
    else:
        m_sm.append(m_sm[-1])
        z_sm.append(z_sm[-1])
        p_sm.append(p_sm[-1]+1)
ans=0
for i,s in enumerate(S,1):
    if s=="-":
        ans=max(ans,m_sm[i]+p_sm[-1]-p_sm[i])
    elif s=="0":
        ans=max(ans,m_sm[i-1]+1+p_sm[-1]-p_sm[i])
    else:
        ans=max(ans,m_sm[i-1]+p_sm[-1]-p_sm[i-1])
print(ans)