using System;

public class Program {
	public void Solve() {
		char[] c = Console.ReadLine().ToCharArray();
		char[] cww = {'c', 'w', 'w'};
		int index = 0;
		int count = 0;
		bool flag = false;
		for (int i = 0; i < c.Length; i++) {
			if (c[i].Equals(cww[index])) {
				flag = true;
				index++;
			}
			if (flag) {
				count++;
				if (index == cww.Length) {
					Console.WriteLine(count);
					return;
				}
			}
		}
		Console.WriteLine(-1);
	}
	
	public static void Main(string[] args) {
		Program program = new Program();
		program.Solve();
	}
}