Codeforces Round #547 (Div. 3)B. Maximal Continuous Rest

B. Maximal Continuous Rest

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Each day in Berland consists of nn hours. Polycarp likes time management. That's why he has a fixed schedule for each day — it is a sequence a1,a2,…,ana1,a2,…,an (each aiai is either 00 or 11), where ai=0ai=0 if Polycarp works during the ii-th hour of the day and ai=1ai=1 if Polycarp rests during the ii-th hour of the day.

Days go one after another endlessly and Polycarp uses the same schedule for each day.

What is the maximal number of continuous hours during which Polycarp rests? It is guaranteed that there is at least one working hour in a day.

Input

The first line contains nn (1≤n≤2⋅1051≤n≤2⋅105) — number of hours per day.

The second line contains nn integer numbers a1,a2,…,ana1,a2,…,an (0≤ai≤10≤ai≤1), where ai=0ai=0 if the ii-th hour in a day is working and ai=1ai=1 if the ii-th hour is resting. It is guaranteed that ai=0ai=0 for at least one ii.

Output

Print the maximal number of continuous hours during which Polycarp rests. Remember that you should consider that days go one after another endlessly and Polycarp uses the same schedule for each day.

题意：求给定整数序列（只由0,1构成）最大连续1的子序列长度，有所不同的是这个序列是一个环，其实就是两倍长度的该序列了，