#include<bits/stdc++.h>
using namespace std;
int main(){
  int n;
  cin>>n;
  string s;
  cin>>s;
  vector<pair<char,int>> v;
  for(int l=0,r=0;l<n;l=r){
    while(r<n&&s[l]==s[r]) r++;
    v.emplace_back(s[l],r-l);
  }
  int m=v.size();
  int ans=0;
  int rp[m+1];
  rp[m]=0;
  for(int i=m-1;i>=0;i--){
    if(v[i].first!='+') rp[i]=rp[i+1];
    else rp[i]=rp[i+1]+v[i].second;
  }
  int lm=0;
  for(int i=0;i<m;i++){
    if(v[i].first=='+'){
      ans=max(ans,lm+rp[i]);
    }
    if(v[i].first=='-'){
      lm+=v[i].second;
      ans=max(ans,lm+rp[i]);
    }
    if(v[i].first=='0'){
      ans=max(ans,lm+rp[i]+1);
    }
  }
  cout<<ans<<endl;
}