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;
class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)){
			int N = Integer.parseInt(sc.next());
			int x=0;
			int maxX=0;
			String S = sc.next();
			for(char c:S.toCharArray()){
				if(c=='I'){
					x++;
					maxX=Math.max(maxX, x);
				}else{
					x--;
				}
			}
			System.out.println(maxX);
		}
	}
}
