import java.util.Scanner;
 
public class Main {
 
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		String str=s.next();
		
		int count=0;
		for(int i=0;i<str.length();i++){
			if(str.charAt(i)=='n'){
				count++;
			}
		}
		
		System.out.println(count);
	}
}