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

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