import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import static java.lang.System.in;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String S = reader.readLine();
        int counter = 0;
        for (int i = 1; i < S.length(); i++) {
            if (S.charAt(i) == 'n') {
                counter+=1;
            }
        }
        System.out.println(counter);
    }
}