#include <bits/stdc++.h>
using namespace std;
int main(){
	int cnt = 0;
    string a = "while";
    string s;
    cin >> s;
    for(int i = 0; i < 5; i ++){
    	if(s[i] != a[i]) cnt ++;
	}
	cout << cnt;
    return 0;
}