/*
ID: indy901
PROG: beads
LANG: C
*/

#include <stdio.h>
#include <stdlib.h>

int N;
int i;
char* beads;
char* newBeads;

int breakNecklace() {
	int startBeads;
	int endBeads;
	int j;
	int k;
	int gotColor;
	char color;
	
	newBeads = ( char* )malloc( sizeof( char ) * N );
	k = 0;
	for ( j = i; j < N; j++ ) {
		newBeads[ k ] = beads[ j ];
		k++;
	}
	for ( j = i - 1; j >= 0; j-- ) {
		newBeads[ k ] = beads[ j ];
		k++;
	}
	startBeads = 0;
	gotColor = 0;
	for ( j = 0; j < N; j++ ) {
		if ( newBeads[ j ] == 'w' )
			startBeads++;
		else if ( gotColor ) {
			if ( newBeads[ j ] == color )
				startBeads++;
			else {
				j--;
				break;
			}
		}
		else {
			color = newBeads[ j ];
			gotColor = 1;
			startBeads++;
		}
	}
	endBeads = 0;
	gotColor = 0;
	for ( k = N - 1; k > j; k-- ) {
		if ( newBeads[ k ] == 'w' )
			endBeads++;
		else if ( gotColor ) {
			if ( newBeads[ k ] == color )
				endBeads++;
			else
				break;
		}
		else {
			color = newBeads[ k ];
			gotColor = 1;
			endBeads++;
		}
	}
	return startBeads + endBeads;
}

int main() {
	int candidateBeads;
	int maxBeads;
	FILE* fp;
	
	fp = fopen( "beads.in" , "r" );
	fscanf( fp , "%d" , &N );
	beads = ( char* )malloc( sizeof( char ) * ( N + 1 ) );
	fscanf( fp , "%s" , beads );
	fclose( fp );
	maxBeads = 0;
	for ( i = 0; i < N; i++ ) {
		candidateBeads = breakNecklace();
		if ( candidateBeads > maxBeads )
			maxBeads = candidateBeads;
	}
	fp = fopen( "beads.out" , "w" );
	fprintf( fp , "%d\n" , maxBeads );
	fclose( fp );
	free( beads );
	free( newBeads );
	return 0;
}