#include<bits/stdc++.h>
using namespace std;

int main(){
  int n;
  string s;
  cin>>n>>s;
  vector<int> cp(n+1);
  for (int i=0;i<n;i++) cp[i+1]=cp[i]+(s[i]=='+');
  int ans=0;
  int cm=0;
  for (int i=0;i<n;i++){
    cm+=s[i]=='-';
    ans=max(ans,cm+(s[i]=='0')+(cp[n]-cp[i]));
  }
  cout<<ans<<endl;
}