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  • P4099Salad Bar
    限制 : 时间限制 : 10000 MS   空间限制 : 165536 KB
    问题描述

    Bytea went to a salad bar. There are  fruits one next to another on the bar counter. Specifically, these are apples and oranges. Bytea can pick any contiguous part of the line of fruits for her salad.

    The fruits she chooses will be added to the salad either from left to right or from right to left. As Bytea loves oranges, she requires that throughout the salad making process, the number of oranges in it should always be no smaller than the number of apples, regardless of whether these are added % from left to right or from right to left. Help Bytea out by writing a program that will find the longest contiguous part of the line of fruits that satisfies her requirements.

    输入格式

    The first line of the standard input contains a single integer  (), denoting the number of fruits. The next line contains a string of  characters  (). These stand for Polish names of apples and oranges: jab\l{ka} and pomara\'ncze). Consequently, if , then the -th fruit in a line is an apple, and otherwise it is an orange.

    You may assume that in tests worth  of the total score , and moreover that in test worth  of the total .

    输出格式

    The first and only line of the standard output should contain a single integer equal to the number of fruits in the longest contiguous part of the line that satisfies Bytea's requirements. Note that it could be the case that is the correct result.

    样例输入

    6
    jpjppj

    样例输出

    4


    来源  poi2014 bzoj3521