package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Scan(); d, _ := strconv.Atoi(sc.Text())
	sc.Scan(); s1 := sc.Text()
	sc.Scan(); s2 := sc.Text()
	s := s1 + s2

	max_h := 0
	for i := 0; i < len(s); i++ {
		var h = 0
		var u = d
		for j := i; j < len(s); j++ {
			if c := s[j:j + 1]; c == "o" {
				h++
			}else {
				if u > 0 {
					u--
					h++
				} else {
					break
				}
			}
		}
		if h > max_h {
			max_h = h
		}
		fmt.Println(i, h)
	}

	fmt.Println(max_h)
}