Increment Decrement

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

inputFormat

Input

The input is given from Standard Input in the following format:

N S

outputFormat

Output

Print the maximum value taken by x during the operations.

Examples

Input

5 IIDID

Output

2

Input

7 DDIDDII

Output

0

样例

5
IIDID

2