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 C++14 (Clang 3.8.0) (judge verdict: Accepted)

//
// B - Increment Decrement
//

#include <iostream>

using namespace std;

int main() {

    int N;
    string S;

    cin >> N;
    cin >> S;

    int x = 0, max_ = 0;

    for (int i = 0; i < N; i++) {
        if (S[i] == 'I') {
            x++;
            max_ = max(max_, x);
        } else {
            x--;
        }
    }

    cout << max_ << endl;
}