import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        char[] arr = sc.next().toCharArray();
        TreeSet<Integer> cPosition = new TreeSet<>();
        TreeSet<Integer> wPosition = new TreeSet<>();
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == 'c') {
                cPosition.add(i);
            } else if (arr[i] == 'w') {
                wPosition.add(i);
            }
        }
        wPosition.add(Integer.MAX_VALUE - 2);
        wPosition.add(Integer.MAX_VALUE - 1);
        int min = Integer.MAX_VALUE;
        for (int x : cPosition) {
            int y = wPosition.higher(wPosition.higher(x));
            min = Math.min(min, y - x + 1);
        }
        if (min > arr.length) {
            System.out.println(-1);
        } else {
            System.out.println(min);
        }
    }
}