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: Wrong Answer)

#include <stdio.h>
#include <string.h>
int main()
{
    int n,x=0,max=0,i;

    scanf("%d",&n);

    char id[n+1];

    for(i=0;i<n;i++){
        scanf("%c",&id[i]);


    }
    id[n]='\0';


    for(i=0;i<n;i++){
            if(id[i]=='I'||id[i]=='D'){
                if(id[i]=='I'){
                    ++x;
                    if(x>max)
                        max=x;

                }
            if(id[i]=='D'){
                --x;
                if(x>max&&x>0)
                    max=x;

            }
        }


    }
    printf("%d",max);



    return 0;
}