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)

#include<stdio.h>

int main(){
	
	char buf[101];
//	char buf[3];
	int N;
	int x=0;
	int i=0;
	int max = 0;
		
	fgets(buf,100,stdin);
	sscanf(buf,"%d",&N);
//	if(N < 1){
//		N = 1;
//	}
//	else if( N > 100){
//		N = 100;
//	}

	fgets(buf,101,stdin);
//	fgets(buf,3,stdin);
	
//	printf("%s", buf);
	
	
	for(i=0; i<N; ++i){
		if(buf[i] == 'I' ){
			++x;
		}
		else if(buf[i] == 'D'){
			--x;
		}
		if(x > max){
			max = x;
		}
	}
	
	printf("%d\n", max);
	return 0;
}