You have an integer variable x. Initially, x=0.

Some person gave you a string S of length N, and using the string you performed the following operation N times. In the i-th operation, you incremented the value of x by 1 if S_i=`I`, and decremented the value of x by 1 if S_i=`D`.

Find the maximum value taken by x during the operations (including before the first operation, and after the last operation).

Constraints

* 1≤N≤100
* |S|=N
* No characters except `I` and `D` occur in S.

Input

The input is given from Standard Input in the following format:


N
S


Output

Print the maximum value taken by x during the operations.

Examples

Input

5
IIDID


Output

2


Input

7
DDIDDII


Output

0

import java.util.*;	
public class Main {

	public static void main(String[] args) {
		int x = 0,max = 0;
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String c = sc.next();
		for(int i = 0;i < c.length();i++ ) {
			if(c.charAt(i) == 'I') x++;
			else if(c.charAt(i) == 'D') x--;
			if(max < x)max = x;
		}
		System.out.println(max);
	}

}
