#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
using namespace std;

int main(){
	int day[30] = {0};
	int ren = 0;
	int max = 0;
	int rest;
	char a;
	int i;
	
	cin >> rest;
	for(int i=0; i<14; i++){
		cin >> a;
		if(a == 'o'){
			day[i] = 1;
		}else{
			day[i] = 0;
		}
	}
	
	for(int start=0; start<=14-rest; start++){
		i = 0;
		ren = 0;
		
		//ゆうきゅうより前
		while(i < start){
			//更新処理
			if(day[i] == 1){
				ren ++;
			}else{
				ren = 0;
			}
			
			if(ren > max){
				max = ren;
			}
			i ++;
		}
		
		//ゆうきゅう
		ren += rest;
		i += rest;
		//if(i >= 14){
			//ren = ren - (i - 14);
		//}
		if(ren > max){
			max = ren;
		}
		
		//ゆうきゅうより後
		while(i < 14){
			//更新処理
			if(day[i] == 1){
				ren ++;
			}else{
				ren = 0;
			}
			
			if(ren > max){
				max = ren;
			}
			i ++;
		}
	}
	
	cout << max << endl;
	return 0;
}