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 (GCC 5.4.1) (judge verdict: Accepted)

int main()
{
    int maxval;
    int i;
    scanf("%d", &i);
    i++;
    char string[i];
    for(int counter = 0; counter < (i); counter++)
    {
        scanf("%c", &string[counter]);
    }
    int val = 0;
    for (int j = 0; j < i; j++)
    {
        if(string[j] == 'I')
        {
            val++;
            if(val >= maxval)
            {
                maxval = val;
            }
        }
        else if (string[j] == 'D')
        {
            val--;
            if(val >= maxval)
            {
                maxval = val;
            }
        }
    }
    printf("%d\n", maxval);

    return 0;
}