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) {
		// TODO 自动生成的方法存根
		Scanner sc=new Scanner(System.in);
		int N=sc.nextInt();
		String S=sc.next();
		int x=0;
		int y=0;
		for(int i=0;i<S.length();i++) {
			String c=S.substring(i,i+1);
			if(c.equals("I")) {
				x++;
				if(x>y) {
					y=x;
				}
			}else {
				x--;
				if(x>y) {
					y=x;
				}
			}
		}
		System.out.println(y);
	}

}
