package main

import . "fmt"
import . "strings"

func main() {
	var n,s string
	Scan(&n,&s)
	plus := Count(s, "+")
	ans := plus
	minus := 0
	for _, c := range s {
		switch c {
			case '+':
				plus--
			case '-':
				minus++
				ans = max(ans, minus+plus)
			case '0':
				ans = max(ans, minus+1+plus)
		}
	}
	Println(ans)
}