import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		String s = sc.next();
		
		String mode = "c";
		int min = Integer.MAX_VALUE;
		
		int L = -1; int R = -1;
		
		
		for (int i=0; i<s.length(); i++) {
			if (mode.equals("c")) {
				if (s.charAt(i) == 'c') {
					L = i;
					mode = "w";
				}
			}
			else if (mode.equals("w")) {
				if (s.charAt(i) == 'w') {
					mode = "ww";
				}
			}
			else if (mode.equals("ww")) {
				if (s.charAt(i) == 'w') {
					R = i;
					min = Math.min(min, R-L+1);
					mode = "c";
				}
			}
//			System.out.println(L+":"+R);
		}
		
		System.out.println(min==Integer.MAX_VALUE?-1:min);
		
	}
}