import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class No00000345_Main {
	static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	public static void main(String[] args) throws IOException {
		String s = br.readLine();
		int cnt = 0;
		int step = 0;
		for(int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			if(step != 0) cnt++;
			if(c == 'c') {
				if(step == 0) {
					step++;
					cnt++;
				} else {
					cnt = -1;
					break;
				}
			} else if(c == 'w') {
				if(step == 1) {
					step++;
				} else if(step == 2) {
					break;
				}
			}
		}
		System.out.println(cnt);
	}
}