import java.util.Random;
import java.util.Scanner;

public class Main {
    public static void main(String args[]){
        Scanner scan = new Scanner(System.in);
        String S = scan.nextLine();
        int num=0;
        for(int i=0;i<S.length();i++){
            if(S.charAt(i)=='n'){
                num++;
            }
        }
        System.out.println(num);
    }
}