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();
		String S = sc.next();

		int x = 0;
		int max = 0;

		for(int i = 0; i < N; i++){
			char c = S.charAt(i);
			if(c == 'I'){
				x++;
			}else if(c == 'D'){
				x--;
			}

			if(x > max){
				max = x;
			}
		}

		System.out.println(max);
	}
}