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.

Examples

Input

5
IIDID


Output

2


Input

7
DDIDDII


Output

0
# -*- coding: utf-8 -*-

#https://atcoder.jp/contests/abc052/tasks/abc052_b

def main():
    x = 0
    N = input()
    S = raw_input()
    
    # アルゴリズムを考えるよりも、 1 <= N <= 100 であるからすべてなめたほうが早い
    x_max = x
    for ope  in S:
        if ope == 'I':
            x = x + 1
        elif ope == 'D':
            x = x -1
        x_max = max(x,x_max)

    print(x_max)

if __name__ == "__main__":
    main()
