You are given a string S of length N. Your task is to find and print the maximum integer present in the string.

An integer is defined as a maximal contiguous sequence of digit characters (0-9). Any non-digit character separates two integers.

Notes

• Print -1 if the string contains no integer.
• Print -2 if the string is empty.

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Input Format

• The first line contains an integer N, the length of the string.
• The second line contains the string S.

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Output Format

Print a single integer:

• The maximum integer present in the string.
• -1 if no integer is found.
• -2 if the string is empty.

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Constraints

• 1 ≤ N ≤ 100000
• The string may contain uppercase letters, lowercase letters, digits, spaces, and special characters.

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Sample Input 1

39
33 milestone is either 12 or 75 km away

Sample Output 1

75

Explanation

The integers present in the string are 33, 12, and 75. The maximum among them is 75.

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Sample Input 2

16
abc123xyz456def

Sample Output 2

456

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Sample Input 3

10
hello world

Sample Output 3

-1

Explanation

The string contains no digits.

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Sample Input 4

0

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