#include <stdio.h>

int main() {
    char szWhile[6] = "while", c;
    int opCount = 0;
    for (int i = 0; i < 5; ++i) {
        scanf("%c", &c);
        if (c != szWhile[i]) {
            ++opCount;
        }
    }
    printf("%d\n", opCount);
    return 0;
}