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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
int main(){
  int c,N, x=0, max=0;
  char S[256];
  scanf("%d", &N);
  scanf("%s",S);
  for(c=0;c<N;c++){
    if(S[c]=='I')x++;
    else if(S[c]=='D')x--;
    if(max<x)max=x;
  }
  printf("%d\n", max);
  return 0;
}