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(void){
	
	int n,x=0;
	int max=0;
	char  str[105];
	int i;	
	scanf("%d",&n);
	
	rewind(stdin);
	gets(str);
	
	i=0;
	while(n>0  &&  n<=100){
		
	
	if(str[i]=='I')
			x++;
	else if(str[i]=='D')
			x--;
	else
	
	if(max<x)
			max=x;
	
	
	i++;
	n--;
	
	}
	printf("%d",max);
	
	return 0;
}