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.* ; 
import java.math.*;
class Main{
  public static void main(String[] args) {
    Scanner scan = new Scanner (System.in);
	int n = scan.nextInt();
    String s = scan.next();
    char[] ch = s.toCharArray();
    int x = 0 ;
    int max = 0;
    for(int i = 0 ; i <n ; i++){
      if(ch[i] == 'I'){
        x++;
        if(x>max){
          max = x ;
        }
      }else if(ch[i] == 'D'){
        x-- ;
      }
    }
    System.out.println(max);
  }
}