import java.util.Scanner;

public class yukicoder_345 {
	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		String str1 = stdIn.next();
		
		int mojisu = -1;
		
		int c = str1.indexOf("c");
		
		if (c != -1) {
			String str2 = str1.substring(c + 1);
			int w1 = str2.indexOf("w");
			
			if (w1 != -1) {
				String str3 = str2.substring(w1 + 1);
				
				int w2 = str3.indexOf("w");
				
				if(w2 != -1) {
					String moji = str1.substring(c, c + 1) + str2.substring(0, w1 + 1) + str3.substring(0, w2 + 1);
					mojisu = moji.length();				}
			}
		}
		System.out.println(mojisu);
	}
}