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 sc = new Scanner(System.in);
	int n = sc.nextInt();
	sc.nextLine();
	String s = sc.nextLine();
	int ans = 0;
	for(int i = 0, x = 0;i < n;i++){
	    if(s.charAt(i) == 'I')
		x++;
	    else if(s.charAt(i) == 'D')
		x--;
	    ans = Math.max(ans, x);
	}
	System.out.println(ans);
    }

}
