A - Extra-terrestrial Intelligence

A -Extra-terrestrial Intelligence

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Time Limit:2000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

Description

input

input.txt

output

output.txt

Recently Vasya got interested in finding extra-terrestrial intelligence. He made a simple extra-terrestrial signals’ receiver and was keeping a record of the signals forn days in a row. Each of those n days Vasya wrote a 1 in his notebook if he had received a signal that day and a 0 if he hadn’t. Vasya thinks that he has found extra-terrestrial intelligence if there is a system in the way the signals has been received, i.e. if all the intervals between successive signals are equal. Otherwise, Vasya thinks that the signals were sent by some stupid aliens no one cares about. Help Vasya to deduce from the information given by the receiver if he has found extra-terrestrial intelligence or not.

Input

The first line contains integer n (3 ≤ n ≤ 100) — amount of days during which Vasya checked if there were any signals. The second line containsn characters 1 or 0 — the record Vasya kept each of thosen days. It’s guaranteed that the given record sequence contains at least three 1s.

Output

If Vasya has found extra-terrestrial intelligence, output YES, otherwise output NO.

Sample Input

Input

8
00111000

Output

YES

Input

7
1001011

Output

NO

Input

7
1010100

Output

YES

题目大意：

给出一串长度为n的只含有0和1的字符串，判断每两个1之间的距离是否相等，如果是，则输出YES，如果不是，输出NO。

代码如下：

#include
#include
#include
using namespace std;
int main()
{
    int i,n,num1=0,num2=0,flag=0;
    char c;
    
    for(i=0;i