using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static long[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var s = ReadLine();
        var minus = new int[n + 1];
        for (var i = 0; i < n; ++i) minus[i + 1] = minus[i] + (s[i] == '-' ? 1 : 0);
        var plus = new int[n + 1];
        for (var i = n - 1; i >= 0; --i) plus[i] = plus[i + 1] + (s[i] == '+' ? 1 : 0);
        var ans = 0;
        for (var i = 0; i < n; ++i) ans = Math.Max(ans, minus[i + 1] + plus[i] + (s[i] == '0' ? 1 : 0));
        WriteLine(ans);
    }
}