#include <iostream>
#include <string>
using namespace std;

int main() {
     string s1;
     cin >> s1;
     string s2 = "while";
     int sum = 0;
     for(int i = 0;i<5;++i){
        if(s1[i]!=s2[i]){
          sum++;
        }
     }
     cout << sum <<endl;
     
}
// 64 位输出请用 printf("%lld")