#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> P;
#define REP(i,n) for(ll i=0;i<ll(n);i++)












int main(void){
	cin.tie(nullptr);  ios_base::sync_with_stdio(false);
	ll i,j;




	ll N;
	string S;
	cin >> N >> S;



	vector<ll> m(N+2,0),p(N+2,0);
	for(i=1;i<=N;i++){
		if(S[i-1]=='-') m[i]=m[i-1]+1;
		else m[i]=m[i-1];
	}
	for(i=N;i>=1;i--){
		if(S[i-1]=='+') p[i]=p[i+1]+1;
		else p[i]=p[i+1];
	}




	ll ans=1;
	for(i=0;i<N;i++){
		if(S[i]!='0') continue;

		ans=max(ans,m[i+1]+p[i+1]+1);
	}



	cout << ans << endl;








	return 0;

}