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>
int main()
{
    char s[100];
    int i,n,k=0,j=0,a[100],b,m=0;
    scanf("%d",&n);
    scanf("%s",s);
    for(i=0;i<n;i++)
    {
        if(s[i]=='I')
            k+=1;
        if(s[i]=='D')
            k-=1;
        a[j]=k;
        j++;
    }
     do{
        b = a[m] > a[m+1] ? a[m] : a[m+1];
        m++;
       }while(m>n);
   if(b>=0)
    printf("%d",b);
   else
    printf("0");
   return 0;
}