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){
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    int cnt=0,max=0;
    String str=sc.next();
    sc.close();
    for(int i=0;i<n;i++){
      switch(str.charAt(i)){
        case 'I':
        cnt++;
        if(cnt>max){
          max++;
        }
        break;
        case 'D':
        cnt--;
        break;
      }
    }
    System.out.println(max);
  }
}