You are give a binary string \(S\) of length \(N\) containing only 0's and 1's. Please find the length of the longest chain of 1's in the string.

Input Specification

The first line will contain the integer \(N\) (\(1 \le N \le 10^5\)). The second line contains the binary string \(S\).

Output Specification

Print one integer: the length of the longest 1 chain.

Sample Input

6
101100

Sample Output

2