Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

5
IIDID

Sample Output 1

2

After each operation, the value of x becomes 1, 2, 1, 2 and 1, respectively. Thus, the output should be 2, the maximum value.

Sample Input 2

7
DDIDDII

Sample Output 2

0

The initial value x=0 is the maximum value taken by x, thus the output should be 0.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);

   String nyuA=sc.nextLine();
  // String nyuB=sc.nextLine();
 
      String[] S=sc.nextLine().split("");

//int n=Integer.parseInt(nyu);

int N=Integer.parseInt(nyuA);
//int S=Integer.parseInt(nyuB);


//long H=Long.parseLong(t[0]);
//long W=Long.parseLong(t[1]);
//long C=Long.parseLong(t[2]);

//boolean[][] data=new boolean[H][W];
int count=0;
int max=0;
for(int i=0;i<N;i++){
if(S[i].equals("I"))count++;
else count--;
if(max<count)max=count;
}

System.out.println(max);

	}
}