USACO1.1.4 Broken Necklace (beads)

/*
ID: xsy97051
LANG: C++
TASK: beads
*/
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
int main()
{
freopen("beads.in","r",stdin);
freopen("beads.out","w",stdout);
char s[700],c='0';
int n,a=0,b=0,w=0,ans=0;
cin>>n>>s;
memcpy(s+n,s,n);//以此处理环的状况

for(int i=0;i<2*n-1;i++)
{
if(s[i]=='w')
{b++; w++;}
else
if(s[i]==c)
{b++; w=0;}
else
{
if (a+b>ans) ans=a+b;
a=b-w; b=w+1; w=0; c=s[i];
}
}

if (a+b>ans) ans=a+b;

if(ans>n)
cout<<n<<endl;
else
cout<<ans<<endl;

return 0;
}