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) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.nextLine();
		char S[] =  new char[100];
		S=sc.nextLine().toCharArray();
		int x=0;
		int xmax=0;
		for(int i=0 ; i<N;i++){
			if(S[i]=='I'){x++;}
			else if(S[i]=='D'){x--;}
			if(x>xmax)xmax=x;
		}
		System.out.println(xmax);
	}

}
