import java.io.*;

public class No418{
    public static void main(String[] args) throws IOException{
        String cry = new BufferedReader(new InputStreamReader(System.in)).readLine();
        char[] chr = cry.toCharArray();
        int ans = 0;
        for(int i=0; i< chr.length; i++){
            if(chr[i] == 'n') ans++;
        }
        System.out.println(ans);
    }
}