C++ :

#include<stdio.h>
#include<malloc.h>
int sum1=1,sum2=1,h1=1,h2=1;
void find1(int i,char a[],int n,int h1){
	int first;
	if(sum1==n-1) return ;
	if(i==n-1) first=0;
	else first=i+1;
	if(a[i]=='w'&&h1==1) a[i]=a[first];
	if(a[i]=='w'&&a[i-1]=='w'&&h1!=1)  a[i]=a[first];
	if(a[first]=='w') a[first]=a[i];
	if(a[i]==a[first]) {sum1++;find1(first,a,n,h1++);}
	if(a[i]!=a[first]) return;
}
void find2(int i,char a[],int n,int h2){
	int first,last;
	last=i-1;
	if(i-1<0) last=n-1;
	if(sum1+sum2==n) return;
	if(i==0) first=n-1;
	else first=i-1;
	if(a[i]=='w'&&h2==1) a[i]=a[first];
	if(a[i]=='w'&&a[last]=='w'&&h1!=1) a[i]=a[first];
	if(a[first]=='w') a[first]=a[i];
	if(a[i]==a[first]) {sum2++;find2(first,a,n,h2++);}
	if(a[i]!=a[first]) return;
}
int main()
{int n;
	while(scanf("%d",&n)!=EOF){
		getchar();
		int max=2;
		char *a,*b;
	a=(char *)malloc(n*sizeof(char));
	b=(char *)malloc(n*sizeof(char));
	scanf("%s",a);
	for(int i=0;i<n;i++)
		b[i]=a[i];
	for(int i=0;i<n;i++){
		find1(i,a,n,1);
		if(i>0)
		find2(i-1,a,n,1);
		else
		find2(n-1,a,n,1);
		if(sum1+sum2>max) max=sum1+sum2;
		sum1=sum2=h1=h2=1;
		for(int j=0;j<n;j++)
			a[j]=b[j];
	}
	printf("%d\n",max);
	}
	return 0;
}