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.Scanner;

public class Main{
    public static void main(String[] args){
	Scanner scan = new Scanner(System.in);

	/* 入力 */
	int n = scan.nextInt();
	String s = scan.next();

	int ans = 0;
	int max = 0;
	for(int i = 0; i < n; i++){
	    if(s.charAt(i) == 'I'){
		ans++;
	    }else{
		ans--;
	    }
	    if(max < ans){
		max = ans;
	    }
	}

	System.out.println(max);
    }
}
