import java.util.Scanner;


public class Y418 {
	Y418() {
		Scanner scanner = new Scanner(System.in);
		String s = scanner.next();
		
		int cnt = 0;
		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) == 'n') cnt++;
		}
		
		System.out.println(cnt);
	}
	public static void main(String argv[]) {
		new Y418();
	}
}