/* -*- coding: utf-8 -*-
 *
 * 3210.cc:  No.3210 Fixed Sign Sequense - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 300000;

/* typedef */

/* global variables */

char s[MAX_N + 4];
int mcs[MAX_N + 1], pcs[MAX_N + 1];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d%s", &n, s);

  for (int i = 0; i < n; i++)
    mcs[i + 1] = mcs[i] + (s[i] == '-' ? 1 : 0);
  for (int i = n - 1; i >= 0; i--)
    pcs[i] = pcs[i + 1] + (s[i] == '+' ? 1 : 0);

  int maxl = 0;
  for (int i = 0; i <= n; i++) maxl = max(maxl, mcs[i] + pcs[i]);

  for (int i = 0; i < n; i++)
    if (s[i] == '0') maxl = max(maxl, mcs[i] + 1 + pcs[i + 1]);

  printf("%d\n", maxl);
  
  return 0;
}