import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int n = scan.nextInt();
String str = scan.next();
char[] s = new char[n];
for(int i = 0; i < n; i++) {
s[i] = str.charAt(i);
}
int cnt = 0;
for(int i = 0; i < n-2; i++) {
if(s[i] == 'x') {
if(s[i+1] == 'x' && s[i+2] == 'x') {
cnt++;
}
}
}
System.out.println(cnt);
}
}