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.*;
//Increment Decrement
public class Main {
	public static void main(String[] args){
		Scanner scn=new Scanner(System.in);
		int N=Integer.parseInt(scn.nextLine());
		String S=scn.nextLine();
		int x=0;
		int max=0;
		scn.close();
		
		for(int i=0;i<N;i++){
			switch(S.charAt(i)){
			case 'I':
				x++;
				if(x>max){
					max=x;
				}
				break;
			case 'D':
				x--;
				break;
			}
		}
		System.out.println(max);
	}
}
