import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[] s = sc.next().toCharArray();
		sc.close();

		int[] a = new int[n + 1];
		for (int i = 0; i < n; i++) {
			if (s[i] == '-') {
				a[i + 1]++;
			}
			a[i + 1] += a[i];
		}
		int[] b = new int[n + 1];
		for (int i = n - 1; i >= 0; i--) {
			if (s[i] == '+') {
				b[i]++;
			}
			b[i] += b[i + 1];
		}

		int ans = 0;
		for (int i = 0; i < n; i++) {
			if (s[i] == '0') {
				int val = a[i] + 1 + b[i];
				ans = Math.max(ans, val);
			} else {
				int val = a[i + 1] + b[i];
				ans = Math.max(ans, val);
			}
		}
		System.out.println(ans);
	}
}